I am not to sure on the code. I was looking at it with my mentor tonight because we kind of wanted to see how the code worked, for certain reasons

. From what i learned tonight is that Limit_Mix is a function. I didn't know if you knew that or not?? I don't see though why your joystick is doing that. We are currently using a older joystick that was i think in the 2003 kit, we haven't really messed with using the new ones. So i don't know if it is just a problem with the new ones or not. I assume you are using the new joysticks that came in the kit? Also if i was you i would check the wiring going to the speed controllers and from the speed controllers, there could be a problem there.
As far as the code you did to correct that problem, i am not sure if that will work or not. Especially since i am kind of just learning C. However i am not sure if you can "legally" do "254-Limit_Mix" i don't know if C will compile that or not.