I had the problem where after 10 years of working fine, my Craftsman
opener opened a foot or so, then closed a foot or so. After reading
through past postings, I did the following:
1) Disconnected the door and retried. Same result, up, then down.
2) Tightened chain slightly, same result.
3) Both up force and down force were on low. Changing down force to
middle of high range and up force to max makes door work normally.
Can cold weather cause this problem, or what part should I look at to
find the cause of the problem?