Got a problem with the tacho on my V8 LX torana (SLR dash, MSD 6 series ignition). It has been working fine for over a year and suddenly yesterday while driving reads about 700-1000rpm too high (seems to get more inaccurate with more revs), even indicates this at idle - ie 1300rpm instead of 550rpm that I know it is. Wondering if anybody knows what could be causing this or what the problem is? I had not done any work of any kind (mechanical or electrical) on the car before the problem and it happened by itself. Oh, and by the way, the tach needle does return all the way to the bottom when the car is turned off. All help greatly appreciated.

Cheers,

Paul E