Finally found that the motor that drives the water trough and ice shovel was 'TRIPPING" on it's attempt to go in the opposite direction. Dismantled everything and after some difficulty pried the rear cover off the motor and scraped off quite a bit of rust that was jamming the shaft where it passed through the rear cover of the motor. Lubricated shaft and nylon gears with silicone spray, reassembled everything and it now works as it should. Cheers, Ed