It’s been awhile since I repaired my 2nd gear, but I recall having to fiddle with that wheel as we dropped the bottom case onto the upper, so that it engaged a wheel on the transmission - I believe it was the 1st gear wheel but could be wrong. Anyway, make a trial run dropping the lower case onto the upper and you’ll see where things have to mess. BTW, dropping that lower case is a two-person job to make sure the shift forks drop into the correct slots.