Installed a new Blue Head, half way through the standard break-in the tachometer stopped showing the rpm. Tach is about 24 to 25 years old (steam). Since the engine is brand new (crate), I'm guessing it can only be 1) one of my wiring connections failed (fuse is still fine), or 2) tach is gone. Any other thoughts and how I might test the tach itself?

Thank you,
Steve