polaris1200slx

I have a 2000 slx 1200 and the starter just spins but doesn't engage. If I turn the drive shaft back and forth while holding the starter button and letting it spin it will sometimes catch and start but the next time or two I try to start it, it's back to the same again. I'm assumeing it's a bad bendix. Wher is the starter? Can I change it myself? How much is it to have it done? Any guidence would be greatly appreciated. I only got to us it one time. I just bought it.