I've had an intermittent problem with the rev counter (the simple digital instrument in the My Panel) which flicks periodically to zero and then goes back to reading sensible numbers.
Today I noted that on the right "mag" the rev counter shows zero full time and the left reads properly. On both the intermittent thing happens.
The engine is running fine.
Any thoughts where to look for this? The Lightspeed troubleshooting guide is of no use as the problem is strictly limited to the RPM read out.