On the side of the motor unit you will find the 'up limit' control. Turn this control 2 full turns in the opposite direction of the arrow printed on the cover.
Your chain coming off is caused by a worn out bearing on the Gear & Sprocket assembly. This is generally caused by a door that needs springs and is much heavier than it should be. The part number is 41C4220A and is available at any good door service company. It should come with instructions.
Answers & Comments
On the side of the motor unit you will find the 'up limit' control. Turn this control 2 full turns in the opposite direction of the arrow printed on the cover.
Your chain coming off is caused by a worn out bearing on the Gear & Sprocket assembly. This is generally caused by a door that needs springs and is much heavier than it should be. The part number is 41C4220A and is available at any good door service company. It should come with instructions.