Question about liftmaster Chamberlain Garage Door Opener Transmitter 300MC

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The utomatic garage door does not work; only works manually. The motor is working because I can hear it.

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It sounds like a gear is stripped in the gearbox which will caus the mechanism not to turn.

Posted on Mar 27, 2011


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1 Answer

Avanti motor garage door only works occasionally can hear realay`s click but motor does not run

The relay contacts are worn. Replace the relay first. If the condition is the same , look at the motor's safety overload device.

Sep 24, 2014 | Building Materials

1 Answer

I have a dalton walton model 3663-372 garage door opener ,just moved in to this house and this garage door never worked properly you can hear the motor working but you can also hear the gears slipping as...

Does the door opener have a cord that hangs down on it with a plastic hand grip on the end of it?
This cord when pulled down puts the door opener in a disengaged manual mode if someone has pulled on the cord.
The symptoms you are presenting could occur if you have one of these cords on your door opener has somehow had someone pulled on it.
From the user manual of your door opened you need to pull on this cord to release the plastic hand grip from the bracket so it will move up to put the door in engaged mode.
see page 47 of the pdf version of

Have a different door opening but had exact same experience of moving in and someone pulled on the cord and then I had to look up the user manual to figure how to put it back in engaged mode.

Jan 15, 2018 | Home Security

1 Answer

I have a Sear Hbw07777 opener and replaced the sensor. the sensor is now working but when i tried the garage door switch the drive would turn, you could just hear the motor turning! whats the problem

It sound like you have a bad drive gear. This is a white nylon gear just in front of the motor. If it is bad it will be obvious. The part number is 41A2817 and it comes with instructions.

Jan 13, 2011 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

Liftmaster 1/2 HP Garage Door opener won't open or close. Has been working fine until I pulled out this morning. The door will move freely if I disengage from opener. Went up ladder to see chain not...

The shaft on these garage door motors are not direct drive systems. You'll have to open up the box to see what the actual problem is. I have had stuff like this happen where a gear just slipped out of place.

Here is a link for a parts supplier. I don't know your model but it looks like most of the Liftmaster worm screw gears and drive gears are plastic so it's possible that one of them has cracked.

Feb 14, 2010 | liftmaster Chamberlain Garage Door Opener...

1 Answer

I have a Sears Garage door opener (139.53800SRT)was working and then just quit working. None of the remotes or wall switch work. When I press a switch I hear a few click in the opener and then nothing. ...

The code for 5 flashes is " Motor overheated or possible RPM sensor failure. Unplug to reset." Also if the door is stuck in the open position it could be the trolley is jammed against the bolt just in front of the motor unit.

Feb 07, 2010 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

My garage door hums but does not open. It had

Sounds like you have a bad start capacitor. It sits next to the motor and is about the diameter of a silver dollar and about 5 inches long. You can get one at any good door opener service company.

Feb 06, 2010 | Sears Craftsman LiftMaster Chamberlain...

2 Answers

Garage door opener won't open or close door

The drive gear is stripped. Remove the cover and you can see it just in front of the motor. It is white nylon and the part number is 41A2817. Available from Sears or any good door opener service company. It will come with instructions.

Jun 06, 2009 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

I have a 1995 Sear garage door opener that stopped working

The trolley (the part that moves back and forth and is connected to your door) of your opener is most likely jammed against the bolt just in front of the motor unit. You can remove the bolt or loosen the chain until your unit will run. Once the door is closed find the 'up limit' on the side of the motor unit and turn it about 3 turns in the opposite direction of the arrow printed on the cover. Now replace the bolt or tighten the chain. Whichever you first did.

May 28, 2009 | Sears Craftsman LiftMaster Chamberlain...

2 Answers


didnt try everything cause if you did, it would work! Get two people and garage door opener. One read manual from car under Garage door" or Homelink while other pushes button. When manual says if this did not work or if you have security plus or rolling code, continue with other instructions. You will need a working remote and will need to pushh learn button on motor logic board.

Dec 25, 2008 | Sears Craftsman LiftMaster Chamberlain...

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