Mechanical tach failure?

wrote in message
...

How about either a change inmagnetic flux or a change in the position
of the EC (Edy Current) ring?

A weakened magnet would cause the reading to DROP. So something that
causes the aluminum disc to get closer to the magnet would cause the
RPM to read high, or something that causes the air movement from the
spinning magnet to influence the disc - like a bit of oil or grease
from the cable migrating into the instrument.

Like I said, everything looked fine inside (no dirt or grease). There is a
scuff mark on the inside of the disk which could be new or old. If lubing
the cable doesn't do the trick, I'll probably send it out to be rebuilt;
unless the cost is more than another used unit.

Thanks,
Rich S.