I have this same problem too. Just changed my clutch, and the internal ball/bush under the shaft, and i still cant get first of fourth without a bloody good wrestle. Had a look at all my bushes, and the bush that holds the long shaft ontop of the steering rack along with the ball on the relay shaft are very worn. I will need to change these out too but will need to let my funds recover. This is without a doubt the cause of my gear selection issues. The 8v boxes are quite strong from what i've heard, so the linkages are most likely your problem.