Scooterotica

What I have here on my bench is an early p200 motor cases that I have built several times over. It's specs are non auto lube and it has the oil seal for the rear axle on the outside. I am using and efl axle, gears and I just rebuild the Cush drive and the clutch is a fancy sip number with 16 springs. All new bearings and seals, I am trying to use only top quality parts.
It took a bit to get the gears to mesh, there is no friction when the crank spins by hand. The cases are closed up and tight, everything seems right.
My trouble is that when I put on the rear hub and tighten the nut, the axle is pulled outward with the torque pulling on it. This causes the gears to bind and I can't turn the crank at all, it's frozen. If I take off the hub and gently tap the axle back inward, the assembly unsticks itself and its back to being perfect. I'd say that the amount of movement for the axle is just a few mm.
So, if Id like to put solid torque on the axle nut, how can I ensure that the axle won't still walk its way out or that the gearing won't bind up on itself?

Any help is appreciated.
Thanks

Could you have a worn or loose in the casing rear hub bearing? Obviously you have the circlip in but I have seen casings where the bearing can move in and outwards between the casing and circlip, maybe this is then allowing the gears to foul on the cluster or cushdrive? I think you will have to strip the motor again to see where it is jamming and if it is the axle moving then maybe a shim on it before feeding it through the hub bearing may cure it.

is it the hub catching on brake shoes (or something ??)....just thinking outside the box..or engine !!

shim

Solved.
The circlip had come out of the groove and it was pulled out about 5mm from its home, with the bearing. So, I just tapped the bearing in and replaced the circlip. Hopefully, it wont walk out again, I mean, if a circlip is in, its in, right? I spun it a bit to ensure that it is seated in the groove. Fingers crossed I guess.
The gears now mesh, all's good again.