Diagnosing root cause of garage door stall
Garage doors have a counterbalance mechanism (usually springs).   You don't actually lift the door, only move it.  When lifting a garage door, you should only be fighting the friction of the rollers in tracks, and the inertia of the door's weight.

It's very important that you keep a door in tip-top condition.  The problem with a binding door is you end up forcing it.  Forcing an already binding door makes it bind more.  And eventually damages the mechanism.  Eventually the damage and spring force tears the door apart, killing someone.  This is serious business, don't turn your back on a damaged garage door. 

The power opener makes you blind

We have a factory with six huge doors on big 240V industrial power openers. Every door had serious problems.  Nobody knew, because when an opener could no longer open the door, they just bought a bigger opener! 

Unhook the opener.  Work it by hand.

You'll find out in a right hurry where the problem is.  (or isn't). 

There are about a dozen things that can go wrong with doors, and other sites have good checkout lists.  Just to name a few:


door rollers wobbly (bearings failed) 
hinges sloppy due to excessive wear
door very hard-moving because it's skewed/trammed (higher on one side) due to slipped drum
unliftable due to counterbalance problem e.g. broken spring, cable problem or loose cable drum.
drifting up/down due to spring too loose, too tight, or wrong spring
door panels bent, e.g. from vehicle hit
hinges badly aligned, causing binding


With our huge doors, each door had at least 3 of these.  Now they open so well we didn't bother reconnecting the openers. 

These parts are mostly standardized and not particularly expensive.