I'm having a problem with my Lift Master Forumla I Whisper Drive garage door opener.
For the last few weeks, the door has frequently stopped part-way down when closing and then gone back up again. Now, for the last couple of days, the door will not go down at all -- at most it goes down a couple of inches, and then triggers to come back up. This happens most of the time -- sometimes it will just randomly work.
If I detach the door, I have the same problem with just the trolley. Most of the time, it will just go a couple of inches and then halt and go back.
I've done the following so far:
maxed out the downward KG pressure -- no effect
checked the sensors -- they seem to be fine (and anyway, I get some movement from the door)
same results from the wall button and the remote
pulled the cover off and visually inspected -- nothing that immediately jumps out as a problem. Also, no smell or noise or anything that I notice when this is happening.
tightened the "chain" (it's really a rubber belt with teeth) -- no effect
Any thoughts of what might be going on? I'm really hoping I don't have to call a pro.
thanks in advance.