Garage door opener bending my aluminum Garage Door. Please help.

[915855]

I have a Chamberlain Security Plus Model 7420 1/2 HP garage door opener. I had been having problems with the remote but I thought that it was the battery. I would have to press the button several times in order for it to open. Today, I kept pressing the remote control button to open the garage door and it would not open. I noticed that from outside the top of the door looked like it bent. I went inside the garage and noticed that the opener was closing the door with so much force that it actually bent the door a little from the top. I immediately took of the chain and was glad when the door went back almost to normal (except for the small dent). I repositioned the chain and tested it without the door and everything look good. When I connected the trolley to the door, the chain would go to the end of the wall and hit the wall and then the motor would still pull the chain causing the door to bend again. I tried it several times and every time that I would connect the trolley to the door, it would happen again. Can someone please tell me what is wrong and how to fix this problem. Thank you in advance.

[Lone Star Charles]

Sounds like your up and down limit switches may not be set properly. Check your owner's manual for proper procedure. You might also check the up or down force limits as well.

[TJR]

You probably need a gear/sprocket rebuild.
It will run fine without the door, but when attach the door with that extra load will make the limit gear inside the opener to skip, because of wear in the top bushing at the sprocket and the bottom bushing at the limit gear.
It can be another issue with the limit assembly.
Anyhow, you need to take a look inside the opener, before you do so please unplug the power cord.
Set the up/down force to about 3-4.

[915855]

You probably need a rebuild.
It will run fine without the door, but when attach the door with that extra load will make the limit gear inside the opener to skip, because of wear in the top bushing at the sprocket and the bottom bushing at the limit gear.
It can be another issue with the limit assembly.
Anyhow, you need to take a look inside the opener, before you do so please unplug the power cord.
Set the up/down force to about 3-4.

I opened the garage opener but the gears did not look warned out to me. I took pictures as seen below. Can you please tell me if you can tell by just by looking at the pictures if I need to replace the gear/sprocket? There was also a washer that was broken as seen in the picture. Thank you.

[TJR]

Most likely it's NOT a broken washer, but part of the bushing at the sprocket and all the debris from it is all the black stuff on top/inside the big white gear.
The two smaller gears you see at the bottom in the second picture are what that control the limit switch, with the wear of the bushing and you connect the door will pull the gears apart and not engaging so the opener don't know when to stop going up and/or down.

[915855]

Most likely it's NOT a broken washer, but part of the bushing at the sprocket and all the debris from it is all the black stuff on top/inside the big white gear.
The two smaller gears you see at the bottom in the second picture are what that control the limit switch, with the wear of the bushing and you connect the door will pull the gears apart and not engaging so the opener don't know when to stop going up and/or down.

Ok, thanks for your help. I will replace the gear/sprocket and keep you posted on how it goes. Thanks again.

[915855]

I went ahead and replaced the gear/sprocket and everything is working good again. For the past week I had to start my car outside in freezing temperatures but now I can park inside my garage. Thanks for your help.

[mygaragerepairsacramento]

Yeah, replacing the sprocket is the way to do it. Had the same issue a few months ago.

[San Jose Garage Experts]

Agree with mygaragerepairsacramento.

[garagedoorsreno]

Yes, if the switches are not set properly, then just replace the sprocket.