Installed a new Chamberlain HD900D and having an issue
I had a 1994 Liftgate belt driven garage door opener shoot craps on me. I bought a Chamberlain HD900D to replace it. I used the same wiring for the sensors and the opener on the wall. All of that works correctly. I used the same brackets from the old opener and installed a new piece on the header of the garage where the previous one was.
Everything works correctly but one thing. The opener opens the garage pretty slow. It then closes slow at start and then just basically lets go and it slams the door on the ground. I went through the steps to set the opening and closing heights successfully. You then have to hit some buttons for the opener to program how the opener is supposed to adjust to opening and closing speeds and such. I have done it multiple times without success and the door slams the ground so hard I have to actually go hold it and prevent it from slamming.