Last year I lost two small parts of the rear cockpit of a Hasegawa F/A-18F. I scanned a copy of the front of the kit instructions and the page with the missing parts. I circled the needed parts in red. I wrote a very simply worded letter saying I'd lost the parts. I mailed the three pages to the address in Japan listed on the instructions near the "form" for replacing parts. About 14 days later I received a very small package with the parts I needed.
A similar situation with Trumpeter was not as fruitful, but I did eventually get the broken canopy replaced with the help of an American who has become an intermediary with the folks at Trumpeter.
Hope this helps.
--
Joe Vincent
IPMS*Memphis