I have a 99 Honda BF50A. I get no reading on the tachometer. I have verified that the gauge is functional, that gray wire from the rectified is continuous and verified that the rectifier is functional (swapped with working unit). Does the rectifer get a signal from a sensor under the flywheel? What is this device called and how hard is it to replace? Any advice on how to check? It is the last thing I can think of and see on the wiring diagram! Thanks