Liftmaster JackShaft Doubletake

[sknaf]

My Jackshaft has a bit of unusual behavior - it open and closes fine.
However if I have the garage open for a couple minutes, and then try to the close -- the first time the door comes down an inch, then goes up and flashes the light.
Trying to close after light flashes with the error, it closes just fine.

So if the garage is open a couple minutes I have to double close. I called Chamberlin, and they said we don't troubleshoot, have a licensed tech come out and tell you. If something is wrong with the unit (which is under warranty still) then we will send parts.

Seems like maybe the unit loses tension or something when the garage door is open and stays open for 5 minutes or more.

Any thoughts about what to look at ?

 

[pima67]

I copied this from my previous post about a LM:
After 3 service calls which "fixed" the problem for a while only to return. I spent over an hour on the phone with LM tech support. After many adjustments, he decided the travel module needs replacing and sent me one. The next service call I told the tech what LM said but he just did some more adjustments but didn't replace the module. When it failed again, he replaced the unit. The problem was that it stopped doing that closing little dance just above the floor and would go back up. I could get the door to stay shut by closing it again sometimes a couple of times in a row. If it happens again, I have the module at hand. The downside is that I watch it to ensure it closed though it's fun to watch the dance. And that he swapped batteries from the old to the new unit.

 

[Wrench97]

Start by lubing the rollers and bearings on the end of the jackshaft.