If the opener was manufactured prior to 1993 it did not come with sensors. It sounds like you may have a combination of problems. I would first check the door springs to make sure one of them isn't broken. Next remove the cover off the motor unit and check the condition of the drive gear. It is white nylon and is just in front of the motor. It should be obvious if it is going bad. On the rear of the motor unit you will find a couple controls. The up and down force adjustments. Increase both of these about 1/4 turn and see if there is any improvement. The normal life of these units is 10 years so you may have a losing cause here. (There are always exceptions though).

It ssems that it tries to work when the chain is going one way but not reverse.

Can someone help me figure this out? Sears .5HP (41A4315-7D) Both of my remotes stopped working around the same time. I have replaced the batteries but no luck. I can still open both doors using the wall controls. If I place the remotes close to the antennas, the doors will open. If I stand out side the garage, neither remote works. I am puzzled that both of motors stopped responding to remotes around the same time. I've tried unplugging the motor for few minutes and reprogramming the unit, no luck. Can someone help?? Thanks.

Thanks for your messages. It was a normal night. not cold or damp. just a general nice evening around 2am. I checked everything out as the cops did as well. nothing we jammed, nothing out of place. the infrared's were all lined up. hasn't done it since either. went up & down about 3x I must say 4 months later my tv did the same thing.I leave it on at night always and it turned on and off 3x as well until i took the controller and turned it off. the controller has to face this tv since it has a small infrared and is in my armoir. needs to be very close to turn off the tv.