I have a 200 Amp panel in my home. I have a circuit that feeds one bedroom and the overhead light fixture flickers. I thought that maybe the breaker was at fault, so I removed it and replaced with a new one. Upon removal, I noticed corrosion or pitting on the area that connects to the power source in the panel. However I installed the new breaker, and the light still flickers. I also plugged in my shop vac to an outlet in that room and it runs, then drops in speed, then goes up to normal, then a few minutes later will drop again. The ceiling light dims at the same time the shop vac drops in performance. I am at a loss as to what to do to correct this. This is the only circuit in the house that exhibits this behaviour. Any help will be greatly appreciated. Thank you.