When Homers head turns on Pinball Party it works fine except the coil is still energized very slightly for a few seconds after his head relaxes, but not the same duration in time, 2 secs, 5 secs..., which results in a buzzing noise. I only noticed it because I turned off the volume to play and could hear it. DMM confirmed voltage was continuing to the coil during the buzzing and goes to zero when stops. In test mode this does not happen. Any ideas?