I've done it in the past and it's not much fun. The cords are under tension and if you happen to let one go and it goes back into the mechanisim, your going to buy a new one because it's gone for good. I use to have a procedure from andersen to get the vinyl loose. But since we have moved I don't have a clue where it is.You pop one side of the vinyl off that is made to pop off and remove the top piece. the sash cord mechanisims are inset under that.

Check the link below for a contact # and they can email you instructions

Here is a link that might be useful: Link to andersen windows

call 1-888-888-7020 for customer service

The process isn't too hard. The left side (from the inside) vinyl jamb liner is actually 2 pieces. Raise the lower sash, remove the screws in the liner and the liner will pop out. Lower the sash, then swing it in to remove it from the liner. The cords can then be removed from the sash. Do the same for the upper sash, then you can remove the head jamb liner at the top. Once that is removed, you'll see the metal boxes that the cords go in to. Unscrew them to remove them. When you call the supplier where you buy your Andersen parts, you'll want to give them the measurement of the visible glass on the sash, so they can match it to the correct unit in the parts catalog. (Do this before taking stuff apart, in case they have to order them from the factory.) Tell them you need the balance boxes for a Narrowline double hung. To install, just reverse the above.
A word of caution: some older units have brittle jamb liners, and you may want to replace them as well. There not very expensive, and it beats not having them when the old one breaks.
You can find a dealer close to you by using the dealer locator on the Andersen website.

Here is a link that might be useful: Andersen Windows

Thanks for the good advise on how to do this. My son and I managed to accomplish this repair without too much difficulty. I did crack one of the jamb liners a little but it still functions. Thanks again

If the liner cracked to the outside, you'll want to replace it before water finds it's way into the crack. That can lead to rot, and major repairs.
Good to hear the project went well!!

I found this old thread and was able to fix one of my Anderson windows. It is pretty straightforward, and the people at Anderson are pretty helpful.

One note, is that the jamb liners have splines on the back. They make a very tight fit into the window casing. When re-installing them, use a hammer and a small block of soft wood to tap them tight into the window casing. I'm just saying this because if you drop and break one of your sashes trying to figure this out, you'll be out another couple hundred bucks.

I also put paste wax on everything that slides. Can't hurt.

Can the cords just be replaced without replacing the entire mechanism? It seems that finding the parts and ordering them is more trouble than it's worth. I can't even find someone to make this repair for me.

I did replace the cords without buying the whole unit successfully. I measured the old cord, cut a replacement, re-wond the spring and held it in place by drilling a tiny hole through the plastic wheel and outer case(then held the wond spring and wheel in place by inserting a small screwdriver though the hole drilled in wheel and outer case), simply installed the string around the wheel, installed the plastic piece that goes into the window on the string and slowly released the tension from the wond wheel. After that I did install 1 small rivet to secure the cover to the case because you have to pry the unit apart for this procedure. All said- under $2 invested and about
20 minutes of work for both sides. Still works fine with no issues.

glad that this worked for you as I have never heard of anyone doing this before.

Dan, I'm going to at least try the rebuild approach! So far, I have the box open. How did you judge the right spring tension for the 'empty' wheel? Did you wind up it to look roughly like the remaining good one, THEN install all of the new length of cord on the wheel, then release the tension? How did you control for Slow release with all that tension in the wound up wheel?

For cord, I have slightly thinner tension cord from recovered discarded sash tracks. I couldnt' find real cord anywhere at retail. The right diameter is all mason cord with no load specs at all!

thanks for any pointers!!

John

The balance boxes are probably less than $15.00 each. Careful on the string you use from what i remember it was pretty strong string. And if the string breaks you will probably break the vinyl head piece and then you will be replacing that as well!

I agree. Must have tension cord and work carefully.

Actually, the cost is 30 plus shipping = 38. That's Plan B!

I was just on the phone with Anderson and ordered 4 of these balance boxes for $92 - cheaper than replacing a whole window, and I have 2 to repair. I was a little surprised to learn that these windows were made from 1962-70, so I really hope I have no trouble with the plastic liner.
Anyway, thanks for the helpful information!

Post up some pictures of the before, during and after process.

They will be helpful to future customers.

Hi. I found this very helpful and I'm ready to start, but... I don't know how to identify the proper balance box by model and I haven't found a cross-ref for that. I know the model depends on window size. Can anyone help?

Can you post up a picture?

Measure the visible glass in either the upper or lower sash (assuming they are the same size). Andersen has a glass size to window call out chart on there site under service/parts. Once you have determined the callout size a dealer should be able to provide you with the correct balance box.

If its Andersen, there is usually a serial number etched in the glass or call them with the glass size like MWM said above.

Instructions on how to replace the balancers on Andersen Narrow Line windows (CIG's):

http://www.windowparts.com/v/vspfiles/assets/images/balance%20replacement.pdf

There is a video also on YouTube: https://www.youtube.com/watch?v=obmqxeMfQmU

I opened up the sash balance mechanism by grinding the staked keepers that hold the cover in place. Then inserting a putty knife into the housing (had to bend the end cover up for access) and over the spools (to protect them), then a flat screwdriver on top of that knife and turning it to pry the cover free. Not much pressure is required, if you have ground enough of the staking away.

I was then able to replace the broken cord with some nylon masons line. I wound the new line around the drum and used it to rewind the spring, repeating until it looked like the other one that was not broken. I then used a small c-clamp to keep it wound and proceeded to place the correct number of wraps of lines on the drum to duplicate the unbroken one (total of 3 ½ turns). Then threaded the line out through the hole in the housing and through the plastic pellet and tied a big knot in it. Then released the c-clamp, while holding the spool with my thumb, and slowly allowing the tension to pull the plastic pellet into place against the housing hole.

(I wore work gloves during the rewinding operation so I could safely hold the spool with my thumb when needing to do subsequent rewinding on it. From past experience replacing tape measure tapes, I was careful to watch for and avoid the spring going ballistic on me. It never really threatened to though.)

Then I replaced the cover so that the ground away posts were in the opening where they belonged and taped the cover on with USPS packaging tape. :) The cover isn't in danger of coming off since it's held in compression when in the installed position.

I wish I had been able to find some heavier line but I think the masons line will likely last well enough. It's rated at 155-pound test. If it doesn't, there is a heavier masons line available that is 216-pound test that I'll replace it with.

A tip getting that left side track back into place without breaking it or hurting yourself is to slather some liquid dish soap onto the window stud. It slid right into place easily after I resorted to that method. It also helps to file the sharp end of the spline on the back of the track so it doesn't gouge into the stud.

It has taken me nearly as long to post this than to replace the broken sash cord line. I hope it helps someone like me who couldn't find any info on doing this and had to stumble through it. I like fixing things rather than tossing them, especially when it only needs a piece of string replaced. YMMV

Nice follow up and write up. I suspect this will help plenty of folks in the future. Well done.

2 years later... Follow up: The mechanism is still working well (gets used almost daily) so it seems the standard nylon mason's line is good enough.

I replaced two complete balances but saved the old ones in hopes of repairing them. I'm glad to find it's doable since we have many other windows that will need repair. Surprisingly a single working balance does still hold the window up. I was hoping to use stranded wire instead of string but that may not work any better. The string has to make a 90 degree bend over a curved metal piece and I can see a wire wearing there or cutting through the metal.

What if you just leave it? Mine work fine without it.

It's just loose and not impending anything.

where can i purchase the cord

An Andersen dealer. You need to window size and the approximately age of the window. They will more than likely need to order the balance box for you.

Its part of the balance assembly. Amazon has them.

Suggestion ... when I need a really strong, small cord, I use kevlar spear fishing line. I use it for repairing wind chimes and all sorts of other projects. It's thin, extremely strong, and virtually indestructible.

Just had to repair Anderson Window Balancer. After taking it apart by grinding even the two crimped tabs on the housing top I saw the wound spring had snapped about 5 inches from the carrier retainer end, not the hub end. Pulled out the spring and the string to get it out of the way, and using the 5 inch broken spring I held it over the gas stove using a pair of pliers to heat the snapped end and I used another pair of needle nose pliers to re-bend the snapped end to look like the good end just to see if that would work, and yes it did. I then took the uncoiled spring, heated the snapped end and holding the spring with Lineman's pliers while using again the needle nose pliers to reform the spring to look like the original. I started to put things back together before I remembered that the string must be put back in the housing first. It took me a little while to figure out the spring has first to be locked on the outer catch and then be wound down into the hub, but with a little time, patience, and some choice words of encouragement, it got done I then hand wound the spring carrier by hand as much as I could and using a flat screwdriver, I made room by the carrier string slot to attach the string while holding the carrier from spinning under the springs tension. I then wound as much of the string as I could, pulled the cord out some more and holding the carrier wound more cord onto it. When the tension on both cords felt about the same, I let it be.

I put the cover back on and used the two countersunk holes on the bottom (on this one I had to drill out the top using the two existing holes as a guide) I reattached the unit to the window frame with two countersunk head screws

Some claim you cannot do this, or they wouldn't want to waste their time, Yes if the spring would have been broke maybe 10 inches in, this may not have been a practical fix, so before going ahead like I did, first order one you can return, and when splitting the unit take a photo of it to remember what it is supposed to look like when you put it back together,

When they were about $15 a piece replacing them was one thing, but now they want $45 each and want you to replace two. Me, I'm retired and on pretty much of a careful budget, so If I can just fix it, I just bloody-well will. If you do have to replace the unit, save the old one somewhere you will remember, you never know when you might need that spring or maybe the cord.