Have Genie Promax2 chain drive garage door opener. Installed new about 5.3 years ago by professional. I have an intermittent, becoming most of the time, problem. GDO is either dead (no power) or will just quit at any time in middle of operation. Wall switch will have no power, STBs have no lighting. STBs and overhead light and wall switch work when short is not occurring. Now, if I gently slap the main unit (on ceiling of garage), the lights come on and it will work. First time, I just gently jiggled the external wires, and it worked. Sometimes then shuts off in mid cycle, seemingly from vibration, etc. Early in this episode, unit was "dead" so I turned it off for a few weeks. Then when I turned it on, to begin to troubleshoot, it worked for about 1 cycle and then became erratic as above.

Small wire external wire connections (all of the small wires connected to screw-downs) look OK and not loose.

Please help me to determine problem and solution. Circuit braker in wall panel seems OK.

Regards,

Bill M.