Craftsman door opener - 'jams' only when closing (w/ no door)
I am having some issues with my Craftsman 41A5021-2D door opener. Its about 9 years old, so possibly near its natural lifespan.
About a week ago, it started jamming when going down. What I mean is that, even with the door itself disengaged, the trolly would attempt to move down somewhere between 1 and 3 feet before reversing, and then having the lights blink for 5 seconds followed by them staying on indefinitely. The sensors were not showing any blockage (the LEDs are solidly lit). I took it all apart and saw nothing wrong. I took off the chain and noticed it jamming even without that on. I then started toying with the controls that determine how far back and forth the trolly moves. After that it magically started working.
A week later, the same thing started happening again. Its pretty random how far it will go before turning back, and whether or not it does it at all. It never has a problem going up, but always going down. Playing with the force controls doesn't seem to change this.
Does it sound like an issue with the sensors or possibly the logic board detecting resistence when there is none? I find it unlikely to be a mechanical issue because it is so inconsistent. Anyone have suggestions?
If I do replace it, I'm thinking about getting a non-craftsman that I've seen with a better warranty. Anyone see a reason to not do this? I am wondering if the install is fairly standard, or if I might end up creating more work for myself if I change to a different brand.
By the way, there was a similar post to this in another thread, but my symptoms are slightly different.