Hey Maxster, Just a note to thank you for the excellent advice. Finally got back to that job, I carefully inspected the ribbon cables and indeed they were worn through!
But guess what else I discovered when placing some cardboard between the cable and
chassis? When I flexed the cable I could actually see that the top two solder connections on the cable were cold joints and would make and break!! Pulled both boards, resoldered them and ran it for three hours, no problems now. Had to shut it back down 'cause I want to make certain it throttles back properly when it hits setpoints. Thanks again. Later, Mike