I just bought a home with a recently installed 1/2 HP Craftsman chain drive garage door opener on an aluminum sectional door. There is no history on who installed it - I suspect it was the prior owner. Anyway, two months after I moved in, the door broke where the lift bar was attached, it was never reinforced. Sears wants me to purchase an owner's manual and won't otherwise help. The door manufacturer does not make a reiforcing bar, so I reinforced the break with a 4' 2" wide x 1/8" thick steel bar. I thought that would be enough. 30 days later, the door is sagging and about to break again at the ends of the reinforcing bar. I intend to try an 8' 2X4" stud next. My question is, is there something wrong with the instllation that is putting too much strain on the door or does it just need further reinforcement?