Also model 139.53626sr covered in same manual. This opener is about 17 yrs old, but hasn't been used everyday. Gar. is storage. Has been working fine & figured it was dust/debris on railings. Dusted off railings & sprayed with WD40 on overhead railings. Worked intermittantly, then stopped. Have unlatched it to work manually in the meantime. Any suggestions? I can do minor repairs b4 I call out the troops.