Jammin Spur and Pinion?

[Rcbros]

So I have the 5mm bore pinion but the spur for my Jammin X1-CR must be a different pitch. I believe its a mod1 pinion but may be a .8.

But even with a set screw on each end of the pinion it gets flung off immediately and there are drastic wear marks on the pinion.

So what gives lol? Which one am I really needing so I can make sure I get this right the second time.

thanks for ur help!