JoeSpareBedroom wrote:
Single width metal door, ancient Genie opener. Door goes about halfway down,
then up again. Disconnected the door from the chain drive and found that it
was imbalanced - the door barely stays open without something propped under
it. Could this be one reason the opener's having problems? Too much weight?



You have already received a lot of good advice, but I had a problem
with such a door opener that took me years to discover. It too was a
Genie chain drive, but WAS balanced at midpoint unlike yours. So this
story may not be of much help:

In my case although the door was balanced at midpoint, occasionally I
found the door reversing during the close operation. After each
failure, I checked for obstructions and never could find one, much less
duplicate the reversing problem. It just happened perhaps one time in
twenty!!

The solution to the problem was that the rollers that move in the side
tracks for the door had some lateral slack. Occasionally this slack
allowed the door to move sideways enough to encounter an obstacle (I
believe it was the cable attached to the bottom of the door) and that
cause the reversing of the door. The problem was it happened so rarely
that when troubleshooting the problem it was not apparent. My solution
was to place a spacer on one of the roller shafts so that the lateral
movement of the door was reduced. This prevented the door from coming
close enough to meet the cable and obstruct the free flow of the door.