GARAGE STOPReplacement Gear and Sprocket for Liftmaster Door Openers (41C4220A)

The product itself was great, but there are some ways to go wrong that aren't covered in most instructional videos.The installation on my Chamberlain 1255LM was fairly straightforward except for the one screw that you can't get a straight shot at. The best tool for that screw is a 1/4" ratchet.You need to watch at least one video so you can see how to pull the little tab at the bottom that holds the lower gear on.Tip 1: Before you do anything, check the balance of the door. When it's disconnected, you should be able to lift it about halfway and have is stay there when you let go of it (catch it if it drops, or you might break a window). If it's not balanced, the tension on the springs need adjustment. This is not too difficult, but it's fairly dangerous, especially if your springs are old, so you might want to bring in a pro. I did mine after watching a video. I bought two 2-foot pieces of rebar and ground down the ends on a bench grinder, just enough so that they fit snugly in the holes of the adjusting clamp. For safety, they need to go in all the way and you should never be in front of them or the spring when making the adjustment.Tip2: At the motor end, put a mark the angle iron and the chain, so you can put the chain back where it was. I don't know what to use for the mark. I used a yellow grease pencil and a piece of blue painters tape, but by the time I got the chain on, the tape had moved and the mark on the chain was gone. It might have worked better if I put a mark at both ends. I was close, but had to do a little adjusting of the Up and Down screws on the side of the unit.Tip 3: When you take the chain off. Hook it on the motor end of the angle iron that runs from the motor to the beam over the door.Tip 3: The the bottom gear of the kit meshes with a small gear to the right of it. That gear tells the system where to stop based on the two up and down adjusting screws on the side of the unit. If there's a gap between the two gears, the motor won't know when to stop. The gap is there because the black plastic housing for the gear on the right has come loose. It snaps in. Make sure it's tight and the gears are in contact with each other.Tip 4: This is the big one. When your gear stripped. The door was likely either all the way up or all the way down. The control unit may be confused about which one it is. On mine, when I reconnected the chain, the door came up and jammed into the stop bolt near the motor. The control unit thought the door was down, so when I pressed the button the door tried to continue going up, then either clicked, hummed, or did nothing (because it was overheated).Here's how to avoid that. While the chain is off. Run the door (it won't move because the chain is off). Watch the big white gear (the one that stripped). Look at the gear from below. When it stops, you can press the button again and it will reverse direction. When it's rotating counter-clockwise, it thinks the door is going down. Clockwise, it thinks the door is going up. Look where the trolley is (the thing on the chain that connects to the bracket on the door). If the trolley is near the motor, make the gear go counter-clockwise until it stops. Then lift up the door until it snaps into the trolley. If it's at the far end, away from the motor. Do the opposite. Make the gear rotate clockwise until it stops. Then move the door until it snaps in.Then put the chain back on. Tighten it so that the middle of the chain is about 1/2" above the angle iron. It was likely too loose, which is what made the gear strip. Get the lock nut as tight as you can.If the chain not exactly where it was before you took it off, you may have to adjust the up and down screws on the side of the unit. The arrows show which way to turn the screw for more or less travel. Adjust the up screw until the door stops about 4-6" from the stop bolt. Then adjust the down screw until the door just hits the floor.

This fit a 2004 Craftsman 1/2hp opener. Worked great. All components were included plus some that I didn’t need or use. Great value.

Annehmbare Lieferzeit. Eingebaut, funktioniert tadellos.

Fairly straightforward to replace broken mechanism. Garage door now up and running.

This gear and sprocket assembly worked great. It took some time to replace all of the parts, but it was well worth it. I now have an operating garage door opener again.Tip: If you're doing this for the first time, watch a couple YouTube videos on how to replace this assembly. There are a couple of professionals who made videos about the process. They really helped.Last but not least, a number or reviewers complained that the holes in the top plate were not threaded. That's by design. The hole is sized for a #10 screw, but your opener could have been built using, for example, a #10-32 or a #10-24 screw. The non-tapped hole accommodates both. The screws are self-threading. Just run your screw through before installation... simple as that. I did mine by hand with a nut driver. A drill would be much quicker.