Hi all, My garage door started misbehaving and finally stopped opening. The other day I closed the garage door but it opened up right away after closing. After a couple of attempts it stopped opening altogether. When I press the opener on the wall the chain just shakes /rattles and gives up. I have detached the door from the trolley and am manually lifting up the door to get the cars out. The gear and sprocket looks fine. But I changed it out just to be sure but same behavior If I disconnect the chain the motor rotates fine. But if I connect the chain back (door still disengaged) all it does is the chain tightens up very hard but the trolley does not budge. The trolley is on garage door end (not on the opener end). I disconnected the chain and pressed the wall switch to make sure the gear rotated clockwise so that it would be as if garage door was closed. With the garage door still disengaged, I connected the chain back and pressed the button on the wall to see if the trolley would reverse. Motor just hums and chain tightens up but trolley does not move towards garage opener side. I am not sure what is preventing the trolley from moving. I would assume the trolley would move from door end to opener end easily with the garage door disengaged Any idea what I should check for ? Should I increase the limits or the force?