Our Sharp Microwave Model R-508FS has just recently started doing some odd things. If you key in a time and press start, it may continue to microwave but the timer will not count down. Or, if you key in a time and press start, it may run for several seconds and then shut off. Sometimes, if you press the stop key, it continues to run until you open the door. It then will stop running.

I checked the 200 amp breaker box and found that the screw for the wire going to the breaker for the microwave was already as tight as it could go. So, it appears that there is nothing more to do with this and I don't think I'll have any more problems with this microwave.

I believe I've solved the problem. I had tried the hard reset but then last night I thought about it and decided that since this house was built 22 years ago, I wondered if the electrician had used the short cut method on installing the sockets for electrical power. So, I measured the voltage at the adjoining socket while heating water. The voltage before turning on the microwave was 122.7 volts. After the microwave was turned on, it dropped down to 107.6 volts. I located the circuit breaker and shut it off and then pulled out the dual socket. Sure enough, they had used the time saving technique of stripping the wire back about 5/8 inch and then pressed it into the back of the socket. I figured it would be better with the microwave pulling 12 amps to just take the wire and wrap it around the screws on the side of the plug, tighten them down and then put it back in the box. Turned the circuit breaker back on and reset the clock on the microwave and did some more tests. No problems so far and when I measured the voltage drop, it went from 122.7 down to 119.7 running at full power. Don't remember the wire size but it was adequate. The only other thing I may try to eliminate any voltage drop would be to go to the master breaker box and tighten down the screw on the breaker going to that microwave outlet. I had tightened them all down in the whole 200 amp box a long time ago, but it probably wouldn't hurt to go thru the whole box again.