Have a very nice Fridgidaire Professional Wall Oven that, other than being a bit noisy, is an awesome oven!

Recently, I've noticed I can set the temperature to a certain degree; it will climb to that degree and alert me. Then the temperature slowly drops. I've only gone as high as 425 but seems to start to decline no matter what the temp setting is at. I then turn off the oven, turn it back on, see that it dropped 40-50 degrees and restart. It then climbs to the temperature again and goes over the same thing.

Some posts have said to reset the thermal circuit breaker in the back of the oven, but then I've read where it wouldn't even get to the high temps if that were the issue. Probably will need to call repairman, but wanted to be somewhat informed so I could talk intelligently about it! Thanks for any advice!