I have a sears Craftsman 1/2 HP. It will open 1/4 of the way and stop. Then it will open a little more if I continue to push the button and I continue pushing the garage door opener until the door finally opens. Once open all the way it will not close at all. It acts like it will close and stops and retracts. I am now having to close the garage door manually and occassionally it will open when I return but it does not close unless I close it manually or keep pushing the button to make it stop and start in the place where it started to retract.