Evan,
Before doing anything else, try easing the nut on the auxiliary shaft ( the 1/2" nut just below the alloy plug on the RHS of the gearbox). If overtightened, this can cause slight bulging of the steel sleeve on the kickstart mechanism, preventing the bendix gear from sliding. If this doesn't work, then you will have to remove the auxiliary shaft. On the RH end of this there is a gear that runs up a helix on a sleeve with a stop arm. This all fits on the aforementioned steel sleeve and is preloaded by a flat wire spring. If this spring has got weakened, the whole assembly spins rather than the gear running up the helix. If you have to do this, it can be achieved with the gearbox in the bike, by removing the sprocket and final drive and working through the aperture - but it's a bit fiddly.
Regards,
Eddie.
