Hello all. I have a Craftsman 1/2 HP Belt-driven garage door opener that was installed in 1998. It recently developed a problem where it only opens the garage door a couple of inches before stopping (although the motor continues to run for about an additional 13 seconds). If I press the button again, it closes just fine (which is almost instantaneous since it only had a couple of inches to go), but the motor again continues to run for an additional 13 seconds. Also, I noticed the belt moves while the motor runs.

Does this sound like a worn belt? I'm not sure if the belt would still be moving while the motor runs if it was worn or slipping. Thanks for any input.