912ULS shy of 500rpms / Rev Counter

Hello,

for all you pilots out there whose motor performs just fine but seems to miss some revs, this is what I stumbled over lately:

As take off, climb, cruise, fuel consumption felt fine, I suspected a faulty rev counter. Bingo!

At the rear it read 100Hz/6000rpm. I fed 100Hz from a frequency generator and my counter showed a lowly 5500rpm. Adjustment was easy, there's a little trim screw at the rear, which I secured with a tiny blob of laquer after calibrating was finished.

Rechecked revs with various frequencies then, rev counter reads perfect across the range.

Juergen