Question about Sears Craftsman LiftMaster Chamberlain Garage Door Opener Wireless Keypad Model 976LM Security+

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GDO repair Nylon drive gear is worn out. Motor screw gear looks fine. Manual operation seems smooth and balanced. The motor seems plenty perky on this older chain driven opener. Is the nylon gear still available from Sears? I copied several numbers from the face plate, none of which were listed as model numbers. 41A4315-7A (listed as a part number) seemed long enough to try. The product field for this posting would only accept the LiftMaster entry. This product is a Craftsman 1/2 hp which is apparently not considered a valid entry for that field.

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If unit is pre 1993 (Safety beam era), Sears will not sell you any parts. Google Liftmaster gear kit. Buy for $25-30. Not hard if you are handy. Buy the complete kit with bearings.

Posted on Jan 15, 2009

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2 Answers

The motor is running but the chain does not seem to engage?

did you check the manual pull up cable maybe in gauged

Jan 04, 2015 | Building Materials

1 Answer

Liftmaster Professional 1/2 HP spindle not turning

Remove the cover from the motor unit and check the drive gear. It is a white nylon gear just in front of the motor unit and will be obvious if it is bad. The part number is 41A2817 and is available from any door opener service company. The part will come with instructions.

Jun 10, 2012 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

When i used my remote to close the garage it will start and stop and the light just continue to blink. the only way i can get it to close is to continue to hold the button down on the wall.

If the door can be pulled up and down manually, and seems smooth and free of restrictions, and doesn't close jerkily.... then there is a fair chance it is the plastic drive gear assembly inside the motor unit has shredded. They only last so long. (Dont know how old your unit is.)

This is what happened on mine. Got a replacement gear assembly for $40 at a garage door installers shop and replaced it. Problem solved. You can actually see a plastic "snow" inside the unit with the cover off where the plastic has shaved over the years. Takes awhile, but not that hard if you're mechanically inclined.

First though, I'd just check to make sure nothing is hanging it up when trying to close. I assume it goes UP just fine, and only gives you this hassle WHEN CLOSING. If all moves smoothly, take the cover off and look for the worn plastic gear and the infamous plastic "snow".

May 24, 2011 | Chamberlain 12HP Power Drive Chain Drive...

1 Answer

My door closes fine, but when opening, it only

Remove the cover from the motor unit and check the drive gear. It is a white nylon gear just in front of the motor and may be stripped. If so you will also find what looks like white sawdust inside the motor unit.

May 15, 2010 | Sears Craftsman LiftMaster Chamberlain...

3 Answers

I have a Craftsman 1/2 HP Garage Door Opener part # 41A4315-7. The D.O.C. cert # is K1027 and the date is 3/93. Several months ago the garage door opener ceased to function. I do not remember the symptoms...

I was not at all pleased with the service provided by FixYa.
I spoke to two different professionals and their responses did NOT help me solve the problem.
Their responses sent me on a time wasting series of steps that were not productive.

Both pros told me the problem was probably with the motor in the Garage Door Opener.
One told me I had to remove and disassemble the motor to read the windings with a multimeter.
I’m glad I didn’t follow his instructions.
Based on two pros telling me it was the motor (which I did not believe) I did a test.
Here was the process for testing the motor:
This is a dangerous process for a person with limited skills.
The test is done with the GDO in place, the cover removed, chain disconnected and power unplugged.
You will need a standard electric appliance power cord with either a two or three prong plug (pigtail).
The other end will be bare wires.
I used a 2 prong cord removed from an old steam iron but any power cord will work.

Remove the white supply wire from the light bulb socket in the GDO.
Attach one lead from the power cord to the white lead and cover all exposed copper wire or connector with insulating electrical tape.
If you are using a 3 prong plug, fold the green ground lead back out of the way and tape it to the power cord.
Make sure the remaining bare wire lead is not touching your body on anything metallic, then plug the power cord into the same socket you would plug the GDO.
Carefully touch the remaining HOT bare wire lead to either the RED or BLUE leads from the capacitor to the motor.
The motor should run.
Mine did just fine …. Nothing wrong with the motor.
I then touched the HOT lead to the other (Red or Blue) capacitor lead and the motor reversed direction …. Perfect.

I don’t know if this is a valid test of the capacitor, but I then touched the bare HOT lead to the Red then the Blue leads INTO the capacitor.
Again the motor ran fine and reversed direction.
I deduced that the capacitor was also working.
There is very little clearance for this last step so do it carefully.

After verifying the motor and capacitor were not the problem I started retracing all other power supply factors.
Ultimately I found I had reversed the bell wire leads from the door safety sensors when I reinstalled the GDO.
I had connected the hot lead from the left sensor to the right sensor input.
This is very easy to do because the two leads are identical.
The GDO will not operate with these leads reversed.
I corrected the connections and the GDO now works perfectly.
This could have been a 10 minute fix if either pro had asked the right question.
I don’t think either pro is aware of this requirement.

When I signed up for the chat the web site indicated I would be charged $12.99.
Now I find I am being charged 19.99 for bad information.
I doubt I will use your service again.

Jim Shane

Dec 01, 2009 | Sears Craftsman LiftMaster Chamberlain...

2 Answers

My Craftsman 1/2 HP Garage Door Opener stopped working. The motor is running but chain isn't moving. The actual door goes up and down fine.

Remove the cover and take a look. I'm sure you will find the drive gear is stripped. It is a white nylon gear just in front of the motor. You can buy one at any good door service company. The part number is 41A2817 and it comes with instructions.

Nov 16, 2009 | Sears Craftsman LiftMaster Chamberlain...

2 Answers

Garage door opens about one foot and remains there.

Check the door springs. You could have a broken spring. Also remove the cover and check the drive gear. It is a white nylon gear just in front of the motor. It is possibly stripped. This is a good time to release the door from the opener and operate it by hand to see just how heavy it has become.

Jun 29, 2009 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

Craftsman Garage Door Opener - Gears need to be fixed

Unplug the unit and remove the cover, usually eight screws, if you see a lot of white dust in the cover check the nylon drive/worm gear, they will need to be replaced.

Apr 10, 2009 | Sears Craftsman LiftMaster Chamberlain...

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