Yesterday I worked from home because the garage door wouldn't open. The motor wasn't making any funny noise, the chain wasn't derailed, and even if it'd been one or the other, I couldn't have fixed it. Our neighbor had noticed that almost all the bolts of the hinges needed tightening, and maybe that was warping the door's going up and down on its rails, so we took care of that, but still the door wouldn't open. The technician imediately figured out the real problem and took care of it. What was it? The big spring at the top of the door that provides torque had cracked in two. Not that surprising, in retrospect. He said that they stopped making wooden garage doors back in 1985, and the house was built in 1980, so this most likely was the original setup. Screw loose and metal fatigue will do that to a door.