B4 help

[Speed Nerd]

Hi all i have recently rebuilt my b4 and gear box followed instructions and break in but everytime i do it as soon as it gets grip the ball diff loosens itself and i can't think what im doing wrong

Any help or info id be most greatfull.


Thanks Speedy

[K-Brewer]

Could b wrong but could u try an turn the diff around so the screw is on the other side?