This is a clip of me and Buster testing out garage door openers. We successfully get the motor to operate.
This unit intermittently makes a loud squealing noise. After recording I loosened the chain and the noise is still there. This leads me to believe the sprocket is rotating in a warped coupler on the gear and sprocket assembly.
This kind of damage occurs when you run a garage door opener with an excess load. If your door feels heavy by hand, go ahead and get a tune up. It's cheaper to have the door fixed before it damages a perfectly innocent garage door opener!
Keypad idea now on the back burner.