There is a washer inside that can be replaced. Shut the water off to silcock, unscrew handle, pull it off and you can unscrew the guts to get to washer and replace.
RJ

better even is to replace whole thing with a 1/4 turn Ball Valve type which has no washers to harden over time.

"better even is to replace whole thing with a 1/4 turn Ball Valve type which has no washers to harden over time."

The unit the OP has is a 'frost prof' unit.

The actual valve is in heated space to prevent freezing.

Just replace the washer.

depending on age you may need new valve packing to seal after you take the thing apart to get to the valve.

The Teflon packing is far better than the old stuff (I purchase the Teflon stuff by the roll).

Thanks for all the help. I'd like to replace it with a 1/4 turn ball valve but I cannot find that type in a frost proof unit. Is it correct that those are not made?

If I decide to replace the washer and valve packing, where can I purchase that? Woodford sells a "repair kit" for 20 bucks but $40 seems steep to repair two sillcocks. I found the washer online for 50 cents and $12 shipping (seriously).

And what is "valve packing"?

good to know I have never owned a house where it went below freezing normally. in Texas the shut-off was always outside with the hose bib. in California the shutoff is inside but the pipe is not insulated anywhere - just a little tape where it enters the ground.

I found this video which completely shows the repair, dissembly and assembly of your model.

Here is a link that might be useful: woodford model 17 repair

I suspect there is no problem with the faucett. The problem is a slight operator error because no one bothered to explain to the homeowner how a frost proof faucet works.

Notice from the illustration, the wall flange is mounted flush with the exterior wall of the structure and there is a long tube which passes through the wall with the actual valve seat and bibb washer on the interior end of the assembly which is within the heated portion of the structure (this is what is technically referred to as a Hydrant).

When water is turned off the stem presses the bibb washer against the seat and the water is cut off on the interior end of the tube. The residual water remaining in the tube from the bibb washer to the mouth of the faucett is intended to then drain out so there is no water in the exterior part of the faucett that could freeze.

Quite often ppl who do not understand the function assume that residual water that still comes out is leaking past the valve so they attempt to further tighten the valve, which only leads to excessive mechanical pressure on the bibb washer causing the washer to be distorted and premature washer failure.

The problem can appear even worse if there is a hose attached that has a closed nozzle on the output end. In this situation as the faucett is turned off the residual water is trapped in the faucett & hose. The actual working pressure drops but both the faucett and hose still remain full of water so if the hose happens to be heated by sunlight the water in the hose will expand and cause a backpressure to the silcock, which is then discharged through the anti-siphon backflow preventer and giving the illusion that the valve is leaking.

Properly a hose should be disconnected from a frost proof silcock as soon as you turn the water off, but in the real world we all know that is seldom if ever done.

There is a quick, simple and cheap solution. Install a plastic "Swiss Tee" on the hose thread of the faucett, then attach the hose to one side of the swiss tee. When you need the hose you can open the swiss tee to the hose and when you want to fill a pail or something directly from the faucett you can switch the hose side off and open the other side of the swiss tee to use the faucett directly.

When turning the water off, open the side of the swiss tee opposite the hose connection and leave it open. The frost proof silcock can then drain in its proper manner.

And make sure to pitch the darn thing to drain and use the IPT threads.

Many are not pitched and hold water.
Make sure you remove the hose to allow them to drain.

Every spring there is a rash of leaking frost proofs that froze and broke when a hose was left attached over the winter.

If they are actually screwed in it is far easier to replace them without access to the far end.
You can remove them and replace them from the outside if needed.

Is a "swiss tee" a 2 way hose splitter?

I like the idea of the setup Lazypup, it would sure save time on connecting and disconnecting hoses while still allowing the sillock to drain and be utilized.

"still allowing the sillock to drain and be utilized."

Only if you remember to open the T valve after closing the sillcock.

OP here. So I repaired both sillcocks with the official Woodford repair kits two years ago. Started using them frequently this week and again find it very difficult to close completely. I realize that some water will trickle out after it's closed but this is a steady stream that doesn't stop and takes several tries and a lot of force to shut off completely.

I know I can fix it with another repair kit, but is it normal for the original parts to last 7 years but the repair parts only 2 years? Should I just keep repairing these things every other year (at 20 bucks a pop) or would you recommend replacement with a different brand? Thanks for any and all advice.

If it were me, and it was not a big hassle to get access to where the hose bibb is connected to the piping, I'd be replacing the whole thing at this point. By the way, when you did the repair two years ago, were there any obvious signs of wear or deterioration of the old parts?

I too had problems with shutting off model 17's, and it wasn't user error or seats as suggested above. I installed four 17's in 2004 and 2005. Two of them locked up frequently when half closed. Replacing gaskets, seats, and rings did nothing. I eventually learned that banging the handle inward usually freed it up. I eventually removed one completely and took it in to my local plumbing supply house to show them. They couldn't figure it out either, even though I could demonstrate it to them on a dry faucet.

I notice that my sillcocks were made within a year of those owned by the original poster. I wonder if Woodford had some sort of manufacturing problem then.

Although this is an old thread, it shows up in searches (which is how I found it), so I figure it's worth mentioning my experience so that others know that it might not be them. I've found it horribly frustrating that most in plumbing forums describe Woodford's as the best sillcocks ever and assume that anyone having problems with them are idiots, and it isn't so.

The Woodford Troubleshooting and Maintenance guide serves as
a visual reference for this comment: http://www.woodfordmfg.com/woodford/Troubleshooting/14%20Troubleshooting.pdf

In my situation, I suspect the inside thread of the retainer
(Fig 3) gets stuck, metal to metal, as the faucet is closed. It feels as though the valve stem has reached
the point of shutoff, yet water freely flows from the faucet. I back up a bit and try again until the valve
seat rubber reaches the faucet seat.
Perhaps hard water reduces the ability of the retainer threads to turn
smoothly during shutoff.

I just used the RK-17MH kit to repair the faucet. While there is some merit in replacing several
parts at one time, all I really needed was the valve seat rubber (part #30008).
This is a common 9/16” beveled faucet washer; I’ll just purchase the washer next
time.

Useful diagram and parts information is available in the
Woodford catalog: http://www.woodfordmfg.com/woodford/Wall_Faucet_PDF/17CATALOG.pdf

I have a Woodford Model 17 faucet in my garage with a hose attached to it. I used it a few days ago and had trouble shutting it off. I had to use a adjustable pliers to shut it off, and then it didn't work well after that, so I got a Model 17 Repair Kit, installed it, and was unable to shut off the water after installing. I then bought the adjustable Stem replacement kit, and same thing, I can't turn off the water with the valve. Woodford suggested gently cleaning the valve housing 10 inches in the pipe, then flushing. I did this, but it still runs uncontrollably when I start up the water. Any ideas?

I suspect that the valve seat is damaged. As noted in their repair instructions, if the seat is damaged, you will need to replace the unit.