Sears Garage door opener
The device is probably 20 years old, and came with the house W/O a manual. The problem is the door will start to close, then stop and reverse, as if it's hitting an obstacle, which it is not. The electric eye is set OK and the tracks are greased. The only way to get the door to close is to hold the "close" button in until it completes the close process. Help, please!