[John-knee]

I've searched around and found plenty of information regarding tachs, but I seem to have a problem not covered...

I have an '84 911.

The tach was working poorly a few weeks ago, then intermittently jumped around dramatically. Sometimes it'll function fine for a few minutes.

Now my tach pins to red line the minute the ignition is turned on. Upon starting the car, in comes off redline and when revved, it reaches 5k. I looks like the tach is operating in reverse, albeit inaccurately.

Battery voltage is fine, hovering around 14volts.

Is it worth taking the thing apart?

Any help would be great!

Thanks