Intermittent Power Fail - Unknown Cause

[DSt]

I just moved into a house with this Whirlpool wall oven/microwave oven combination.  Frequently, but not always, it indicates a power failure at the end of a microwave cooking cycle.  The display lights up and resets the clock to zero.  It has not happened during the actual timed cycle, but always when the cooking is stopped.  Does anyone have an idea why and what I can do to resolve this besides calling a service technician?

Model Number: GMC305PRB01

[Repair-man]

If the board is picking up on a weak power circuit to the unit, perhaps the firs thing to check would be the connections to the oven. Naturally, no one wants to pull a monstrosity like that from the wall, but if there is a loose connection back there, you can waste an awful lot of money throwing parts at the micro. I would also check the breaker connections where the oven wires attach, as these can also cause issues if loose. Pay particular attention to the White (Neutral) circuit going to this unit, because it is the most commonly overlooked electrical malfunction besides a bad breaker.

Other than an actual electrical problem in the house circuit, your main control board on the microwave may be also to blame for the  glitch. I would rule out the first stuff before considering service.

Here's the TECH SHEET for this unit.

[DSt]

As it turns out, Whirlpool knew about this problem, implemented a fix approximately the time my unit was built, but never issued a bulletin.  The repair part is 9760862.  My oven was supposed to have this already, but possibly the first "fixes" were not completely effective.  The power fail would also occur at the completion of the regular oven cool down cycle.  A symptom of the failure is that the clock would reset to 12:00.  A real power failure caused by tripping the breaker would cause the clock to come back up near the time it lost power.  I have the new part to fix my oven, but it is not installed yet, so I will keep my fingers crossed.

[Repair-man]

I show that part to be described as a "wire harness"...what exactly does the part you  got look like and where does it go?