Fluctuating Rev counter

[Polly-Red7]

Hello again one and all,
Whilst driving to work this morning (and again on my return) the rev counter decided to act up?
Once the engine reached normal running temperature and while cruising at a steady 60mph / 2500rpm the needle from time to time would fluctuate between say 2000 and 4000rpm for a second or so before returning to the running rpm? The car itself never missed a beat so I presume the tacho is on its way out? I see from the wiring diagram that its connected to both the coil and distributor, is they're any other checks I should make before seeking a replacement dial?
As always many thanks for your wisdom and replies.
Chris

[John_C]

Check your points dwell assuming you are not running off electronic. Once the points have opened up too much the tacho bounces around even if the car may feel like it's running okay (ish).

[Polly-Red7]

Cheers John, I will look into that.
Chris

[Beans]

If adjusting the points doesn't solve it, you'll probably have to check the wires towards the rev counter.
Check for signs of corrosion or broken wires