Removing the Rear Wheel on a Troy-Bilt Mower?

I need to remove the rear wheel on my TroyBilt Pony riding lawn mower. I have removed dust boot, and center bolt. I thought this would allow me to slide the rim off, but it did not. I have "muscled" it, still no luck. Is there something I am missing that I need to do, or another alternative?

On another problem, when I got the mower out for use this season, the engine cranked right up, but the motor lurches/revs between high and low except in the low position where it idles fine. Anyone wiling to answer one or both questions. It would be much appreciated.