I've got a GE Monogram ZV800SJ1SS vent/hood. The other night it was working fine on the "boost" setting, suddenly the fan speed was reduced significantly. All the buttons seem to work fine, + and - and boost seem to adjust as always except each setting in far reduced. I have it apart - the fan spins fine - no obstruction. The lights work fine. Does not seem to be an inordinate amount of accumulated grease. I tried cleaning all the button switches and ribbon connections with contact cleaner - still reduced speed. Would this be a motor issue or an electrical box issue; capacitor or other?? Trying desperately to diagnose. It has worked great for 10+ years.