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.

  • If you operate the door manually does the door work? Commented Mar 30, 2018 at 14:17
  • Yes. It goes up and down easily on the track when I do it by hand. Commented Mar 30, 2018 at 14:19
  • Sounds like maybe a gear (or other part of the mechanism), might be getting bound up. Remove the cover, and run the opener. Watch any moving parts closely, keeping any eye out for anything that looks like it's binding, jamming, slipping, etc. Be careful not to get your hands, or other body parts into the mechanism or anything electrical. Make sure you also inspect the cog at the end of the track (near the door), to make sure it is spinning freely. Check the track itself, to make sure the trolley is not getting stuck.
    – Tester101
    Commented Mar 30, 2018 at 14:46
  • After the door returns to the open position, do the lights on the unit flash?
    – Tester101
    Commented Mar 30, 2018 at 14:49
  • When you removed the cover, did you notice any plastic shavings/dust inside?
    – Tester101
    Commented Mar 30, 2018 at 14:54

1 Answer 1


You did not state the actual model number so I will not be able to answer with model specific information that would be much more detailed and specific to your situation. So you will not be able to do this blind folded.

Since your sensors are working .. good. Some movement of the door is not an indication they are working - that is an indication they are clear to start with. You could have a loose wire or sensor or circuit board inside the senor that when the Door Moves the vibration causes the beam to break! - been there done that.

Why do the lights on my garage door opener flash and my door will not close

How to align safety reversing sensors.

So if those sensors are Truly fine.

Then check your drive gear, it has a set screw or some means of securing it to the drive shaft that screw may have backed out and or is loose. The gear may turn with no load (in other words no belt connected) but might spin free if there is a load - Remove the belt and you can try to grab the drive gear by hand and hold it from turning while the unit runs. Your motor appears to have a gear box and the belt pulley attached - this style pulley if I am not mistaken is a compression style - so it might not have a set screw but rather the way it is secured causes a compressing effect and the pulley grabs the shaft - in short tighten the pulley to the shaft (it is most likely loose) as I said previous Make / Model number / perhaps picture of the name plate .. might have yielded you detailed pictures and specifics to what you have and you might have had it fixed in less than a minute..

  • 1
    I went and jiggled everything - including the sensors, and now it seems to be working just fine again. You may be right that it was the sensors shaking out of alignment. Fingers crossed that it keeps working. thanks for the help! Commented Apr 2, 2018 at 19:52
  • @FerrisJones Sensors could be the wires are loose (even internally) or that they jiggled out of alignment during door movement. You can modify your mounting system to mount them more rigidly to the wall - some mount on the door track and I think this is a bad thing - they tend to flex and loosen over time.
    – Ken
    Commented Apr 2, 2018 at 20:27
  • The problem reappeared, and I posted another more detailed question here: diy.stackexchange.com/questions/138562/… Commented May 12, 2018 at 19:53

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