Bmw top box parts needed

Hello people
The top box on my Gs has been getting abit stiff and I have managed to strip a few teeth from the big plastic cogs there fore it won't work now.

I popped into Bmw but they tell me I can only buy a hole new box and not the internal parts.

Has anyone found a place to buy new parts for the Bmw boxes?
Thanks.

will it be possible to clean the teeth up on the cog with a dremel