The door meets something on the way down and does not reverse, or reverses late
Why it happens
The safety reverse acts on physical contact with objects in the path of the door, which is how B&D states it works. Steel-Line's OL4 manual ties correct behaviour to the down-force adjustments being right, saying that where they are correct the door reverses within one and a half seconds of contact.
Why it matters
B&D states that the automatic safety reverse ensures personal protection from death or serious injury if trapped under a door while closing. A door that opens and shuts normally every day shows nothing about how it behaves in that moment.
Response
Testing the opener and its safety reversal is a published inclusion of a Deadlock Garage Doors service.




