Hey Robotech, why are you resigning yourself to a $200 paperweight? Send an email to [email protected] explaining your problem. Great Planes is the exclusive US distributor of OS engines, and their service is second to none. They'll at least try to fix it for you.

Try slipping a piece of fuel tubing over the joint between the needle valve and the seat. If that doesn't work, the leak is probably in the joint between the needle valve seat and the backplate. Crank that down good and tight, too.