Yeah, that must be it, as this thing is impossible. I just painted the back of the prop, pointed the engine into the sun perfectly, and with the tach held EXACTLY A CERTAIN WAY, well above and behind the prop, it would agree with my other tach for a few BRIEF moments. Other than that it was all over the place.

Major bummer as it is a true hassle to send things back anytime, but especially from here in Mexico.

Thanks,
AV8TOR