It may surprise you that the problem behind the largest number of service calls to garage door specialists is not with the door itself, but rather with the automatic reverse mechanism, more exactly the misalignment of the photo eyes.
Here’s the scenario. You’re getting home from work and press the remote to open the garage door. At this point, everything is working smoothly, as it should. You close the door by again pressing the remote, but after barely starting to lower, it suddenly reverses direction and goes back up!