warped tires

Giving them a slow cook in hot water then allowed to cool should return them to their original shape...unless they were molded that way. Boil a pan of water, then turn off the heat and let stand for five minutes to cool...drop in your tires and let them sit in the water submerged for five or ten minutes. If they want to float, place a small plate or hold them under with a potato masher or wire basket used for steaming that fits inside the pan.

Depending on the type and severity of the warpage you might want to try placeing the parts in hot water (not boiling!!) until thay are maleable then straighten them out.

If this doesn't work you could try searching on Amazon or Ebay for the same kit. Purchase it make RTV moldsof the part(s) you need and then cast them up. Now you have two kits without missing parts. You can always sell the extra kit or just build both!