Recently the tachometer on my '87 300 SDL has been working intermittently. There does not seem to be any rhyme or reason as to when it will or will not work. I did recently have the engine mounts replaced, what a difference in the smoothness of the engine, but the problem was happening before the engine mount repair. It sounds like a loose connection somewhere and I do not know where to begin looking. I dont want to start under the dash because it is a pain to get to. Where on the engine are the wires/sensors to check? Any other suggestions?