My PC and set up is about 3 months old. I have air cleaned it but to no avail. If there is junk in there, air won't cut it. Try isopropal alcohol on a swab like they use to clean tape decks.
Rollers sticking are pretty common.
A final test would be to borrow someone else's mouse with the same kind of connection. You can mess with the ball or the rollers while the computer is on but don't unplug it while it's on. Hope that helps if you are still working on it. My PC and set up is about 3 months old. I have air cleaned it but to no avail.