X-Maxx needs a stronger kushdrive

[HEADSOFTNER]

I put a leopard motor and max 5 esc in my X-Maxx. I also got the bigger gears from ADRC all day rc I can't keep the spur gear from spinning on the kushdrive shaft I drilled and put an axle grub screw threw the shaft that worked for about 5 minutes it keeps snapping the grub screw now we welded it right to the shaft was wondering if there is anything I can do differently cause I really didnt want to weld it but it seems that's the only thing that's working for now but thats going to be a pain in the *** to change spur gears and stuff like that any info would help
Thanks Chris

 

[olds97_lss]

Got a photo of the parts your having issues with?