I have a Sears Craftsman garage door opener 139.53970SRT. I have a doorbell-style opener and three remotes. Without warning, the door will sometimes open or close. I am looking at the three suggestions in the manual:

1. Check all remotes and see if the button is stuck.
   
   2) Short in the "bell wire" (the wire to the doorbell remote).
   
   3) Clear the memory of the unit and all remotes and then reprogram.
   
   Does anyone have any OTHER suggestions or has anyone heard of this happening before? Thanks so much in advance.