Since the cylinder is relatively new, I'm guessing it's the housing that it fits into that has now worn out. There are mechanical pieces in the both pieces, so both are subject to wear. I had issues a few years ago and I replaced both units just to be safe and it's been fine since. IIRC, I bought my cylinder from www.autopartsway.ca
and my housing from www.pelicanparts.com
. The cylinder was well less than $100 which is a fraction of the dealer price. The only problem is that you end up with a different key.