Otis hydro, no prints. Doors work fine during normal operation. If you hit the safe edge or the door open button as the doors are closing you get loud vibrating noise from the door motor (7300) and the doors shake as they are reopening slow.

chain is slipping on sprocket

You and I must have ESP. I just called my tech and told him to check the chain and sprocket.

Also check that the sprocket isn't slipping on the output shaft of the door motor.

Progress?