If you don't have anybody at field, or LHS you can trust with it. I would sent it back to YS. That way your dealing w/ somebody that is honest and very, very knowledgeable of the engine. You also don't have to worry about sending your money and motor to some person and never getting your motor back.

go to the forum title manufactors support. Look for YS, start you a thread in there for Dave to respond w/ shipping address.

In my opinion this is the safest and best way to get the motor fixed.