Hi there!
Got a couple of suggestions off the top of my head.
There should be info in the instruction sheet to get in touch with Tamiya for part replacement. Sometimes, manufacturers send them free.
Try Scalemates.com they have all kinds of info on kits and maybe you can get lucky there.
Lots of guys use e-bay as a source for parts. It's worth a try.
Hang in there. You'll probably get more replys from the members here. You could also post your question in the Auto section here.
Hope I've helped a little. Good luck in your search.
Stay safe.
Jim 
Main WIP:
On the Bench: Artesania Latina (aka) Artists in the Latrine 1/75 Bluenose II
I keep hitting "escape", but I'm still here.