[HayZee518]

both tracks need to be plumb and parallel with each other before allowing any door travel. the counterweight spring(s) need to be tensioned to allow free travel of the door. the door limit switches are always adjusted for minimum pressure to reverse direction (current limiting relays) for the down direction. sensor lights are there for a reason don't use without them. the sproket may be made of hylon or steel and a nylon bushing and repeated motor torque stripped out the gear. it is highly unlikely that the chain or the sprocket teeth would wear to the point of failure after "just a few months" of service.