In all my years of repairing Liftmaster openers the most common malfunction is the gear and sprocket assembly. Either the chain sprocket has sheared off because of the chain being too tight or the plastic gear that turns the chain sprocket has worn off the teeth of the gear due to unbalanced garage door spring or springs or a broken spring making the door extremely heavy and easily wears off the teeth of the plastic gear. The next most common problem I have come across is safety sensors not aligned properly or one sensor has broken. Sometimes its just a matter of objects in the garage in the way of the infrared sensors causing the garage door to not close. If the RPM sensor has malfunctioned then the opener will open and close and stop in random positions.

Liftmaster openers

If Liftmaster openers do not do anything or make any noise when activated by a wall button or remote the main control board may be damaged due to power surges. If the door is not stopping at the normal position and wants to keep closing the door then the limit switch assembly may have a malfunction and sometimes can be easily repaired very seldom need to be replaced.

The least common problem which is hard to diagnose are frequency issues with the receiver caused by outside wireless internet equipment or some other kind of frequency interference which can make the unit open or close on its own and are rare but it sometimes happens because of all the new wireless technology that we use at home these days.

Liftmaster & Craftsman brand openers are the most reliable

Overall in my opinion Liftmaster/Craftsman brand openers are the most reliable on the market today. They seem to last a bit longer than other brands before they start to malfunction and are easy and inexpensive to repair without having to purchase a new opener unit. I recommend Liftmaster/Craftsman brands to my customers because of their reliability. A new Liftmaster/Craftsman opener that is properly installed by a professional should last 10-15 years before any problems occur.