If your opener is clicking, humming, or not responding to the remote, the first thing worth checking yourself is the wall button and the photo-eye sensors - a dirty lens or a sensor knocked a half-inch out of alignment causes more no-reverse complaints than anything inside the motor housing. Vacuum the lenses, check for a blinking light on each sensor, and see if that clears it.
Past that, we'd rather you call than take the cover off the motor unit. Capacitors and gear assemblies inside these boxes don't forgive guesswork, and a door that drops while someone's underneath it is not a repair worth doing solo. If the opener runs but the door is slow, noisy, or uneven, that's usually a spring or track problem riding along with the opener symptom, not the opener itself - worth mentioning when you call so we bring the right parts.