I was sifting through the last years topics, and couldn't find the one on bench testing. So I am asking for some help. I pulled the tach from the dash. It had worked for a couple of years, then one day decided not to work. I know the light blue wire is ground, so that leaves dark blue, brown, gray, and pink. I remembered reading about using a drill with an old distributor and battery. I don't remember how it all gets wired together. If the bench test doesn't work I will need to send the tach out. I hope somebody has had success with getting their tach fixed. I need my tack to work again. The more gauges to gaze at the better. Love to cruise in my '67. Thanks boys!