I have 3 single garage doors with 3 Sears openers. Two openers close correctly. The third opener has periodically caused the door to hit too hard and reverse. I adjusted it per instructions in the manual but after a while it would happen again.

In order to stop the problem: I adjusted it so that it stopped slightly above the floor leaving a small gap. That worked for the past several months - but just now when I came home the door hit the floor with a bang (surprised it did not reverse) and stayed against the floor.

I am wondering why it changes. Any thoughts?