Try putting a pan full of water on the burner and see it it changes.

A burner with essentially no load is not going to control well at high settings.

Following up on what was just said, I'm assuming you were trying this with plenty of water in either a large kettle or a large pressure canner. However, I'm still not sure I understand precisely what is happening.

What I understand is that coil burners cycle on and off to maintain heat. (Smoothtop radiant electric burners do the same thing.) The higher the heat setting, the more they come on and the longer they stay on. When you turn the knob to the "8" setting, you are asking for a lot of heat. if you've got a canning kettle or pressure canner on your burner, it may take a while for the controls to sense enough heat in the pan for long enough to switch off for a while. Go any higher, and the burner may stay on a lot longer simply because of the size of your pot and the amount of water in it.

So, is this a situation that you can get pots to boil with the high setting, but need something slightly lower to maintain the proper pressure setting or keep the boil where you want it the your water bath for your jars?

With that in mind, I can think of several different possibilities for what might be happening and things you could check.

(1) It is just hard to find the exact right temperature with the dial set-up the way it is. Maybe all of these Kenomore stoves do this. Try finding some canning forums and asking there. You might get more specific responses if you start a new post which lists the model number in the title.

(2) Also, you could try calling an appliance repair shop or two and see if they can shed any light on this being or not being a common problem. Either they've heard of this before or they haven't. If they have, they can tell you what needs to be done and give you an estimate. Go to Sears Parts Direct and see what the parts cost. If you are handy enough, you might tackle this yourself.

(3) The rheostat or sensors in your particular stove might have been defective from the start, If you are handy enough to tinker with your stove, you might might try buying just one new controller/mechanism and see if that fixes the problem. If they are not expensive and a replacement fixes the problem, you've found your solution.

(4) Maybe there is something wrong with the coil burner itself. They are easily removed and checked for physical damage or degradation. (They just plug and unplug.)

Sorry I do not have any more specific information than this. GW members tend to look at posts with numbers of responses. So, maybe this will inspire somebody else to chime in with better information.

I had a Frigidaire coil cooktop before. Mine was a 1991 exact replacement of a 1961 model, two 8" burners and two 6", if I remember correctly. Mine also had 9 heat levels, with round knobs that you had to push in to turn, then when you got the the desired level the knob would spring back up. On 8, the coils would be partly orangish/reddish. On hi the coil was orange/red. Once it was at those levels, it stayed, it didn't go on and off at all. And it was glowing red whether or not it had a pot on it. When you say there is no control from 8 to hi, what do you mean? As far as I can remember, mine only clicked into each discrete level, so it was either on hi or 8, for instance. I'd put it on hi to boil water, then bring it down to 8 after the pasta went in so it didn't boil over, for example. But it would boil on 6 if you gave it long enough. Does yours adjust between the levels on the cooler settings, but not at 8?

do all the coils do this or just the one?

The model number for the stove is: 628.9968213

Both large burners do this. They have a fine range of control from low to 8, at which point it jumps from say 75-80% power all the way to 100% power.

The problem is that to maintain the proper pressure I need to set it at ... say 85-90% power and it isn't there.

I'm guessing at percentages, but hopefully it illustrates my point.

The switches do not have discreet levels, there are adjustments between the levels, and yes, Ginny20 seems to describe it well ... it "adjusts between levers on the cooler settings" but not at 8 and above.

Am I making sense this time 'round? It's very clear in my mind what's happening, but I don't know that I'm communicating it well.

Thanks all!
Jim

Both large burners are 2600 watt "canning burners."

That's clear enough.

Another question, though. Do your burners lose controllability above 8 for everything you do or is this mainly a problem when canning.

I ask, because I remembered that a good friend has a special "canning element" for her older coil-burner stove.

When she wants to can things, she swaps out the standard 8" burner and swaps in the 8-inch canning element. It looks like a much beefier version of the standard element. The burner is supported by a heavy-duty delta-shaped base.Apparently, the standard tab supports can bend and the elements can deform under the heavy weight of canning kettles full of water. (Maybe that has happened with your Kenmore?) The heavy duty construction also raises the large water-bath kettles and pressure canners higher off the stove top. IIRC, it was maybe 1/2 inch higher. That keeps the kettle from bottoming out on the stovetop and maybe helps with heat regulation.

I believe that there might be a replacement receptacle that goes with it. If so, that might help with temperature regulation on large canning pots.

If you have not already looked into canning elements, you might try researching them.

Your burner controls are analog, mechanical/rotary. Not particularly unusual that the behavior may not be fully linear due to discrepancies in mechanical tolerances.

The control does not directly sense the temperature of the pot or pan unless there's a temp sensor incorporated into the burner. Some ranges in the past did have such a feature, usually on one burner, often called "burner with a brain" or something similar, and the heat control for that burner was marked in degrees (like an electric frypan). Otherwise the control simply cycles the element on/off for a given heat level, typically via a simple bi-metal mechanism in the control.

Congrats on successfully solving the problem!