About a week ago, my garage door opener (Genie Screwdrive Pro) started making a very loud buzz sound while the door moves.
All the google searches for buzz or hum from an opener either point to a constant hum all the time (transformer) or a loud buzz and no movement on the door (start capacitor).
However, mine still operates just fine, and the buzz only happens when the motor is running.
The motor unit is securely fastened to the garage ceiling, it's not loose or rattling that I can tell by shaking it with my hands (both parallel to the center rail and perpendicular).
Is my start capacitor about to die on me? Would that be a symptom?