Chamberlain Liftmaster Professional Formula 1 motor, probably about 20 years old. The door operates smoothly and easily by hand without the motor. Both springs replaced about 2 years ago.

In the last couple of years the motor sometimes stops on the way down, usually in cold weather. Increasing the down force a little has helped. Increasing it too much it triggers the reverser when it hits the floor. This year, with the cold weather arriving, there is a vanishingly small downforce setting where neither problem occurs.

Aside from that, and especially in other than very cold weather, the door works nicely, smoothly, quietly.

Any similar experience where downforce is either too little, causing partial closing of door, or too much causing reversal when it reaches the floor?

The problem sometimes happened, but not as often, before I replaced the springs but has been getting more frequent each winter. When I replaced them, I weighed the door and chose springs rated for the weight, and tested them. I tested again today in the cold and the door remains at rest at any position and I can raise or lower it with one finger at any position.

  • 1
    Are your springs set correctly? I believe the springs should be set so that the bottom of the door can be raised manually to about 4' off the ground, and neither roll up nor down from there.
    – Huesmann
    Commented Nov 29, 2023 at 14:07
  • @Huesmann, tested and added answer to end of Question.
    – jay613
    Commented Nov 29, 2023 at 14:16
  • 1
    My father had a closer that did the same thing. We had to pull on the door in winter to get it to close. It's probably a failure of whatever mechanism detects force. I'd replace the unit. For one that old it's probably not worth your hassle.
    – isherwood
    Commented Nov 29, 2023 at 15:05

1 Answer 1


At 20 years old, the tiny computer in the GDO is probably suffering some component failures. I've lost laptops at half the age, while others have carried on far longer.

If you really want to go that way, and if it's available (possibly not at that age, but also quite possibly since there isn't a lot of variation in guts between the myriad models) you could probably replace the control board.

Last time I did that it was half the cost of a whole new opener, and the control board was non-returnable and had zero warranty, unlike a complete new opener. I only did it because I knew it got zapped by a nearby lighting strike, and it was quite new.

The road to insanity is replacing components on a board not made to be serviceable, if you're feeling a bit crazy. I'd recommend the wholesale replacement of the entire unit as more efficient if you value your time at all. But if you want to attack with a soldering iron, assume all/any electrolytic capacitors are suspect, and the force-setting potentiometer might be good to replace as well given the symptoms. Beyond that you're down to looking for physical signs that may not be there, since there's unlikely to be adequate detailed information to support component level troubleshooting.

  • There is another road to Insanity in the other direction ... The scope creep that comes with replacing the whole motor. May as well ... Wifi, camera, battery, wall mount (will make space to hang another kayak), do the other door too.. It turns into a $1500 shopping spree.
    – jay613
    Commented Nov 29, 2023 at 17:45
  • Well, there's always: Since you have the springs properly adjusted, open it by hand. Could have a negative cost if someone wants to buy the old opener "for parts." And you can hang another kayak.
    – Ecnerwal
    Commented Nov 29, 2023 at 19:43
  • To be specific: one of the first electronic components to fail from age are capacitors. They're often used for filtering noisy signals so when they fail, you'll often see problems related to signals that make large changes very quickly. These signals will then tend to bounce, creating large spikes whenever there's a sudden transition. The signal from the force sensor might be bouncing when the door hits the floor, and the spike goes high enough to trigger the safety reverse mechanism.
    – bta
    Commented Nov 30, 2023 at 3:19
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    Troubleshooting bad electrolytic capacitors can be pretty easy. They tend to bulge at the top, eventually bursting open. Pop the cover and see if you see any that exhibit these symptoms. If so, you very likely have a bad circuit board.
    – bta
    Commented Nov 30, 2023 at 3:33

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