Have a 1989 Sears GDO that allows the door to slip down a few inches after fully opening. Door is well balanced. No problems or hangups while operating. Any suggestions?
Disconnect the opener from the door and then raise it to the same position as the opener does and release it. Does the door stay put? Your door could be traveling too far in the up direction. Maybe after 20 years the opener is just tired. Yours is not a normal complaint.