Need help with an old Genie SD9000 Model 12A

[Joebowler98]

I know this is a 20+ year old opener but I think the motor is still strong. When I go to open it starts to go then gets hung up and makes a noise like its not connecting to the screw drive "grinding or slipping noise. If I pull the release cord and slide the door to the open position then lock it again and press the button to close it travels down smoothly and closes. I was thinking it might be the part that travels on the screw drive that you pull the release cord on. Any thoughts? I see the part available on Ebay for about $12. Not sure how to replace it but thought about taking a flyer on it and trying it. Is there an adjustment on anything else I might try first? I would really like to not have to replace it here at Christmas time if I don't need to. Any help would be greatly appreciated!

[TJR]

Yes, it is the carriage that's worn out, the black piece that go back and forth. It has a small rack inside it with some teeth into the screw itself and they are probably worn down to nothing and can't reach the screw.