Question about liftmaster Chamberlain Garage Door Opener Transmitter 300MC

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My Liftmaster Formula 1 garage door opener has started to shut unevenly, making one side of the closed door slightly higher than the other. This leaves a gap under the closed door on one side. The door uses 2 horizontal torsion springs each of which get torqued-up by its own pulley and cable system as the door closes. On inspection, I found that when the door is fully open, (i.e. no torsion), the cable which ?winds up? the torsion springs has a little more slack on one side than the other. Thus, as the door closes, the torsion spring on the ?slack? side does not torque-up as much as the spring on the other side. So, when the door is fully closed, there is less torsion on the spring at the ?slack? side, than on the other side. This causes the ?slack? side of the door to be slightly lower than the other side when the door is fully closed, and hence the observed problem. My proposed solution is to adjust the cable pulley on the slack side to even up the slack on both sides. I see the 2 adjusting bolts on the torsion pulleys, and, of course when the door is open there is no tension on the cables, so I assume that as long as I make the adjustment in the door-open position, there should be no danger from the springs. However, before I start adjusting, I?d like to hear from somebody who has had the same problem and can confirm that my diagnosis and proposed fix are correct Thanks Dave

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My friend had the same problem and yes that is what we did. It took a wile to set it evenly. Wouldn't think it would take long but it did. We inadvertently set them to tight and door wouldn't close it would reverse on itself because of the added tension. In the end we did get it though.

Posted on Feb 04, 2010

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