Before I explain how to replace garage door rollers I need to explain how dangerous it can be. The majority of the rollers on a garage door are pretty easy to replace. Its the rollers at the bottom that can hurt you. Also the ones at the very top of the door can be tricky. The first thing you need to know is what hole to slide the roller stem into. One hinge on the sides of the door only has one slot so its obvious where to put the roller stem. The other hinges will have 2 slots to slide roller into. The correct slot is the one that is furthest away from the door. This is critical because if you put the roller in the wrong slot it will make the door rub against the door jamb and make it to tight and keep door from moving up and down smoothly.
As far as tools needed you will need a drill with a bit that can fit a socket at the end of it. Garage door technicians use impact drills. This type of drill uses a back and forth ratchet action that is identical to the type of air wrench that your local mechanics use to remove your tires with.
If you do not have a impact driver than a regular drill should be sufficient. To get started you will have to remove the hinges by unscrewing the screws that hold it to the door. Remove hinge slide out the old roller and slide in the new roller in the exact same slot as the old one. Then when putting the new roller into the track properly you have to angle the roller to hook into the track so that it is secure and not outside of the track. Once the roller is completely inside the track than you can start putting the screws back in the same holes they were in.
Top rollers
When doing this you have to be sure not to tighten the screws too much because you can easily strip the holes out and make an easy job more difficult. If this happens you have to find a bolt and nut to put in place of just the metal screw. Now you have to deal with the tricky top and bottom rollers. The top rollers will need an extra person and a ladder to hold the top section against the wall while you replace the roller. Because once you take off the top bracket the panel will want to come down. Just remove and replace the roller just like the others. Put all screws back in the same holes they came out of. Now we have to deal with the ever dangerous bottom roller.
The bottom roller is the most dangerous roller because it is tied into the torsion springs that lift the door. When the door is down the springs are fully loaded and need to be dealt with extreme care. Do not ever attempt to remove the screws on the bottom bracket while the door is in the down position, you will regret it. There is 2 different ways i replace this tricky roller. The safest way is to un screw the vertical track and slide it up enough to slip in a new roller then put it back the same way you removed it. You should also have someone help by holding that side of the garage door so it doesn’t fall in when you remove the track. Once the bottom roller is replaced then you have been successful. And i repeat this should be done by a qualified technician for safety reasons only.