My trusty Creator Pro, roughly 2 years old, has begun having serious filament jam problems in the right nozzle, the one I use most. The filament gets stuck with a blob on the end and a thin place in the middle, in such a way that it can go neither forward nor back. These photos show the anatomy of the problem. This came on gradually, with more and more frequent jams, more and more difficulty inserting filament and getting it to go all the way down. It took things apart and put them together taking great care to align everything properly, but no help.

Then I started using my left nozzle, and it loads and unloads with all the smoothness I used to be accustomed to on the right.

Is this a familiar experience? Is there some part of the printer that wears out?