HELP - front sprocket nut keeps coming loose.

Need ideas on why my sprocket/nut keeps coming loose.

I'll tighten the shit out of it and punch the edges of the sheath and it'll work fine under normal conditions but as soon as I downshift or pop the clutch it just starts slipping.

It's happened three times now.

Hoping it's nothing major - I'm heading out to disassemble it now.

Yeah, this doesn't look good at all.

I'm not sure the axle is supposed to look a like a bottle cap.

Ouch, that just aint right, it must have come loose and spun the teeth off, hate to say this but you might have to pull the motor and dig into the motor, sorry bud.