Heat limit switch on Sears water heater


I thought I could do this without help, but it got too complicated for me.
I have a Sears Kenmore 153.318560 52 Gal. Power Miser 8+ electric water heater.
It has two elements, two thermostats, and two heat limit switches. One thermostat is bad, but I don't know how to tell which??
It would help if I understood how it worked.** If the top heat limit switch trips, does that cut off power to both heating elements?
If the bottom trips, does that cut off power to both or only the bottom one?
**(The wiring diagram in the owner's manual doesn't show enough detail.)
On the web it said to feel to know if only the top of the heater was hot, or all of it, but I can't feel any heat from any of it.
So far I only know that the top high limit switch tripped. I haven't tried to reset the bottom one.
Background: Three days ago, no hot water so I turned off the breaker, opened the top cover, saw the button for the TOP heat limit switch, pushed it, and had hot water for maybe a day. After that, again only very lukewarm water, so I pushed it again. The following night, the water was up to 170 degrees!, but too tired from work to work on it. The next day, down to 150, and 6 hours later, down to 145. The only hot water I used during that time was the water to fill the powder room sink immediately above the water heater.
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I can't answer your specific questions about your heater but your initial problem can be caused by a burned out element. Some thermostats only switch one of the two hot wires. If the element covering is melted, a small current can flow from the unswitched hot wire, thru the element, and thru the water to ground. This gives you very slow heating that does not stop when the thermostat opens. It will get very hot (enough to trip the limit switch) when no water is used and very cool when water is being used. Check it out.
Don Young
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wrote:

I had to read this 4 times to understand it, but now I can't find what wasn't clear. Your entire paragraph seems clear. Maybe I was tired last night, or I'm just slow.
Thanks. I will check it out.

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