Replacing a defective roller requires you to unbolt the affected hinge, tip the hinge outward from the door to disengage the roller from the track, and reverse this procedure to reinstall with the new roller. You will probably have to tap the hinge bolts out with a hammer before the hinge will release from the door. If you do this, thread the nut back on a few turns before tapping, or you may damage the threads on the bolt. As an additional safeguard, you can also use a small block of wood as an intermediary between the hammer and the bolt if space allows. The door should be in the down position if possible, unless you are working on the lower rollers. Read on!

When reattaching the hinge, tip the roller back into the track, and position the hinge. Tap the bolts back through from the outside, if possible. Garage doors use a bolt known as a carriage bolt. There is no gripping surface on the bolt to hold while you tighten the nut. Rather, it has a square lip below the smooth head that presses and locks into the wood of the door. If you try to tighten the nut without tapping the carriage bolt in first, it may not engage into the same square hole it made in the door originally, and could strip out the wood and begin to turn. Then, you will have to hold the end of the threaded part of the bolt with pliers while you tighten the nut with a wrench. It's good for you to know this trick because older garage doors often show some rot around the bolt openings, especially near the ground, and the carriage bolts may turn no matter how careful you may be!!

Murphy's Law dictates that fate will occasionally trash a garage door roller, or force it out of the track, when the door is in the raised position. And, to compound our misery, the bottom rollers are attached to the same assembly that the garage door cable is attached to, so these rollers must be replaced with the door up! The repair procedure is the same for all hinges... just be sure to remove the tension from the garage door cable if doing the bottom rollers!

1. Use any creative method at your disposal... ladder, 2x4, significant other... to brace up the door panel before you unbolt the hinge. Without this reinforcement, the door will at best sag and at worst break.
2. If you are dealing with a bottom hinge, remove all tension from the cable or disconnect it from the bracket. Remember that the weight of the spring itself exerts a good amount of force, so, if disconnecting the cable is too difficult (some cables are permanently attached to the lower bracket, making replacement an art form), clamp the cable to the track, leaving a little slack on the roller bracket side!
3. Do the roller replacement routine described at the beginning of this section.
4. Once all bolts are fastened down, remove all clamps, braces, etc., and test door manually a few times. Then, reengage the garage door opener, if you have one, and make sure it works smoothly. The end.