When the wall unit or the remote button is pushed to lower the door, it goes down about 6-8 inches then goes back up. Sometimes it will go down about 2 feet then back up too. Once it goes back up, the light clicks on and off like 9 times. I assume this is some kind of code. I have looked at the sensors. Cleaned them. Lined them up properly. And both green lights are on, and they seem to be functioning properly. I have also adjusted the down force screw on the box and nothing has helped. The only thing visually that worries me is that the chain is very loose and hangs down past the T-rail about 3-4 inches. Never noticed this before so this may not be an issue, but thought it was worth mentioning. I have read hundreds of posts on here all the way back to 2005 on this subject but could not find anything that has fixed this issue. I do get it to go down sometimes by holding down the wall unit button or the remote. But that isn't working much anymore. So before I go buy a new unit I wanted to get any thoughts that anybody may have. You guys on here are pretty darn sharp and I look forward to your feedback. Thanking everyone in advance. Take care.