serial #139.663953

This am wife went out and opened the door. the chain came off track.

This evening when i got home from work I reinstalled the chain.

I then engaged the door with the chain. I pressed both buttons on the wall mounted switch. The door closed.

I hit both switches again and nothing happened. I did this a few times and still nothing. I then pulled on the cord which disconnects the door from the chain and it popped like it was under pressure. I then hit both buttons on the wall mount and the motor just hummed. It eventually stopped. I pressed the buttons again and the motor began to hum again but not move.

Does anyone have anything to suggest? Any help woould be most appreciated.

Many thanks

Cliff