Well, before you go and assemble everything just to test, put the shifter back on the left side of the shift shaft and turn the shaft inside the clutch basket (or the inner basket if it's still attached) and try shifting through each gear. If the chain is on, you should only be able to "click" it into each gear but not turn the inner basket anymore once it's in gear without rolling the quad but you should be able to click through all 6 gears and neutral just by "rocking" the input shaft.