Have a Liftmaster 1/2 hp garage door opener by Chamberlain, model number 1265LM. My problem is that the door will not open all the way. Sometimes it opens a 1/4 inch, sometimes it will open 3 feet. It will take 10-30 tries before it opens all the way. The door opens fine while operating manually, meaning even when unhooking the door from the chain, so that the chain does NOT pull the door, the chain itelf will still only open 1/4 inch to 3 feet. SO I have ruled out a binding issue with the door itself. I have oiled chain, rollers, tightend and loosend the chain, have adjusted the travel limits. Sometimes I can get it to work for a couple times, then right back to not working properly. Taking cover off the moter, the small plastic gears look fine, the large one looks like its been used, but I wouldn't say its damaged. Wondering if its worth trying to fix or just buy a new opener. Thanks

Zoso43512, I'm having the same problem, what did you do to fix this?

I found the answer to this: On the rear side of opener, take off the plastic piece covering the light bulb. You will see two blue dials. On the dial on the left side, adjust it turning it 10 degrees clockwise. See page 25 of the owner's manual relating to adjusting the force when "the door doesn't open at least 5 feet".