My garage door opener (LiftMaster 1/3 HP) stops partially through the cycle of closing the door.
I have removed the chain from the gear attached to the sprocket, and tried cycling it like that. I wanted to see how it performed with no weight to lift.
The problem persists. Even with no chain attached, the thing stops before it gets to the "bottom" position.
Also, I noticed that the stopped position of the sprocket is not all the way to the electrical contact for the "top" of the door.
So in other words, something is jamming the sprocket to only be able to move a couple feet between the full-up and full-down positions.
I just finished replacing the sprocket assembly, and this problem still persists.
What else could be causing this problem? The motor? The worm gear? (Worm gear looks fine upon visual inspection). Or is it just time to get a new opener? I believe the current opener is about 15 years old.