I was doing a remodel and the dryer was moved out into a vacant room. The dryer was purchased in 2010. Now was a good time to take the drum out and check all the parts. The dryer was working all right but why wait for a breakdown. There was a lot of build-up of lint in the exit tube which in my case went vertical to the roof one floor. I vacuumed everywhere. Though the drum bearing was good I replaced the drum sleeve without replacing the bearing a much bigger job. I also replaced the four slides that the drum rides on and the drive belt. Now I feel confident it has many more years of trouble-free operation.
The best help was the videos on the AppliancePartsPros.com site on how to replace parts.