First of all, thank you for providing such a wealth of great information!
I have a Kenmore 700 series electric dryer (110.67741600) that is about 6 years old. The unit will turn on/tumble, but stopped producing heat a few days ago and I cannot determine what my next steps should be.
Here is what I know/tested:
Opening door does illuminate light and stop the dryer from tumbling.
I have done the following:
-Validated no exhaust obstructions internally and externally - good
-Validated power from wall at back of dryer/under console - good (120/120/240)
-Validated thermal fuse (via continuity test)- good
-Validated 3 thermostats (via continuity test)- good
I did buy/replace the element already as I thought that was going to be the issue - tested new element and is good.
- Tried testing door switch - believe it is good - there are 3 wires (white/brown/blue); when switch is pressed/closed white+brown show continuity as does white+blue - and believe that is correct.
-Performed a 'timer test' (set timer to typical setting used; unplugged dryer from wall; removed red/black/blue wire harness from back of timer and tested continuity across blue+black) - good
-Started checking wires for possible broken wire between thermostats - so far good - only thing odd but believe is correct is one of the thermostats (cycling?) with 4 wires (2 purple/2 red) does not pass continuity across smaller connectors (purple wires), is this correct?
- checking around motor, pulled wire harness off, wires/connectors looked good;reseated harness.
--did note another switch under tensioner pulley, removed wires,tested as good. wires tested good as well.

I was noting all of this while torn down/testing.
After putting everything back together, the dryer worked great for about 8hrs.<confused>
During regular timed load, wife called me in as no power to appliance and timer was at 30min mark (she starts all at 80min). Could smell the tinge of small burn coming from timer area, but could not see anything. Unplugged device; tested timer (blue+black) with timer on regular selection still; tested ok (continuity showed closed). Went to breaker and it was tripped, reset and went back to appliance. Appliance had power, left console down but unsecured, and restarted. Shortly after starting, a spark shot out from under the left side of console and appliance stopped. Validated breaker tripped again; flipped over console and could trace the smell to timer and noted that the red power wire on upper right was discolored at end and also noticed a charred mark against the mounting surface of console at same corner.

Now that the timer actually has shot sparks I know it has to be replaced. What confuses/concerns me is that the timer test I'm using still passes and the appliance still turns on, but again without heat.
Is there a better test I could/should be using other than that blue+black continuity test? What does that actually test for or prove?
Is it possible that the timer has been failing and that it began working for a short time after being jostled around and then crapped out?

Just trying to find out if there may be a different root cause and the timer was a symptom of that root cause.
I know I have to replace the timer now, but what could/should I test for and can I do that prior to replacing the timer?
What could I be missing or what should my next steps be?

Thanks in advance!
Billy