Call was for "no heat" on an OTR.
Got out and the problem was a little more complicated -- the no heat is intermittent and doesn't follow any pattern the customer can find.
This model cooks on both sensor (popcorn and baked potato settings, for example) and on strict-time cook. The customer tells me both can work well or fail.
Door switches test correctly, before and after use. No resistance over .3 ohms.
I was able to access the diode and capacitor, they test correctly.
I ran the unit for two minutes and got a rock solid 120 VAC out to the high side from the control board.
I then ran the unit a few more times, and it worked every time. On one of these times, I did an amp draw and it was a rock solid 15 amps, no variation. Label says 1800 watts so this is bang on.
Right as I was telling the customer I couldn't make it fail, I turned it on and didn't hear it energize. I took the control panel off and turned it on again. This time the amp draw fluctuated wildly between 13.25 amps to 14.5 amps.
I am really not sure where to go with this, other than telling the customer to call me when it's always dead.