My Craftsman garage door opener opens fine. It

Actually on the older Craftsman models, there will be two adjustments. One travel and the other force (or sensitivity). Could also be the safety eyes, but that would cause it not to operate at all. The adjustment screws are usually behind the light cover. Pull that off and go from there. There are direction arrows showing how to increase/decrease force or limit of up and down travel. Hope that helps.

It could be closing too far or the sensitivity could be set too sensitive.

Lube the springs, wd-40 rust may be the whole problem.

If the door hits and the opener continues to move until the rail flexes upward and then reverses - probably the travel adjustment.

Does the door close and stay closed if you hold the wall button down constant until it closes? - this would indicate a safety eye problem.

If the door reverses before it hits the floor or just as it hits the floor it could be the sensitivity or if the safety eyes are mounted to the track they could be flexing enough to move the eyes out of alignment.

Hope this helps.