Hey Oldcoot,
Almost two years ago a bought a Fuji 50SB and had similar problems. The runout of the magneto was so much that I had to return the motor for a complete replacement. Hobby Services were really great in handling this, and even sent me another brand new engine since the replacement was a SA and not the SB I purchased initially. I recently bought the new Fuji 43 because I believe if I should have another problem Hobby Services will stand behind their product again.