Panasonic microwave turntable and exhaust fan doesn't run
I have a Panasonic microwave of 1997 vintage that was working fine till about a month or so ago. The turntable stopped turning, and at the same time, when something is heated in the unit for more than 5 minutes or so, it shuts off and won't allow me to heat another dish inside it for a couple of hours or so. In fact, the LED display turns dark, and comes on a couple of hours later, at which point it is ready for use. The power seems reasonable, based on how hot the food gets, except for the fact that the heating is not uniform throughout the food mass.
Today I pulled it out and saw that there is a fan on the back - I am unable to figure out if it is an exhaust or an intake - but it looks like an intake, as the perforated metal screen is covered with grime, which looked like it was impeding air flow in/out.
Is overheating the problem here?
However, I fail to see a connection between overheating and the turntable/fan. I can understand if overheating causes the system to freeze, and therefore require a "cooling-off' period before using again. So I am wondering if the turntable/fan system problem is causing the overheating. Since the magnetron seems fine, I am inclined to try and fix this. Any ideas would be gratefully appreciated!