I sold my Genesis for the precise reason of the trouble you're now having. I wish you luck! Mine was in great shape when I sold it, but I knew if there was ever a problem, I would have trouble.
Bonnie did have extra cutting assemblies available at the time I got mine; I don't think you can replace just the blade. That is what I was told at the time.
I bought a Rotatrim, and love it more than I did the Genesis, so if you have to go another route, that would be the one to get.
This is the one I bought, and the company I purchased it from. I highly recommend them!