Hi I have a 400ex that I completely rebuilt from the cases up. Before reassembly I checked to make sure it was shifting fine and it was so I kept rebuilding it. Well I went to put it on quad and realized that it wont shift so I tore it back down. I replaced the shift shaft and spring and wire on the shaft. The drum and forks don't show any signs of wear to my knowledge (not 100% sure what they are supposed to look like if they are worn). Anyways I have spent hours in the forums and cannot find anybody with this problem - shifts fine with cases split but wont shift when cases are back together. One thing I have noticed is that the shift stopper doesn't seem to rotate correctly on the cam it seems to bind up. Like ill be able to shift one or two gears but them the stopper arm doesn't go into the correct slot and the shift shaft fork doesn't engage with the drum. I have a new one on order but I was wondering if anybody any other ideas as to why this could be happening?