If you are in Yokosuka, head to the Hobby Shop and see if there is a guy named Ken Morgan there. Talk to him, tell him I (Neal Hartman) sent you there and tell him your issue. He can probably help you out in finding a good place to get help if he can't help you himself. Last I knew, he was running the Hobby Shop.
Or, try to find a guy named Marc Tuell. He drives a WRX wagon, mid to late 90's, nicely tuned, silver color. He may also be able to point you in the right direction.
If you can't find him, one other guy to look for is Paul Depolo. He has an old DR30 RS Turbo Skyline, two tone red/black. It's a beast and the fastest RS on base or in the area as far as I know (provided he still has it and it's still running.)
Tell them all I referred you to them. Hopefully they can help you out.
In loving memoryE.J. Hartman
November 1960-January 2011 Andrew J. Reagan
March 1983-July 2011