I have measured the depth of shoe travel, cleaned both shoe contact points and blades, and measured continuity between shoes. Touching the shoe contact points to transformer fully energizes the coil, which would indicate there is no voltage loss between the shoes and the coil. The voltage at the blades indicates 17v when the unload button is pressed, more than enough power to fully energize the coil. When I move the car off the track in either direction with the button pressed, the coil no longer hums, indicating contact between shoes and blades had existed when the car was centered on the track. It seems the coil is not getting enough voltage to move the arms and the problem would seem to be between the shoe and the blade. Since the track does operate the merchandise car, I can't see that the track is faulty. My next step would be to check the voltage at the coil itself, which would indicate somethings amiss with the shoe contact, I guess.