[Healeys] Speeds, distances, and odometers.

[Rich C]

Gentlemen,

What is the cause of a speedometer with a perfectly smooth speedometer 
needle that has an odometer that seems reasonably close, but a trip odometer 
that is about 20% out? I thought they were driven by the same shaft.

This speedo went to Nisonger's for just that problem, but ended up getting 
(apparently) a full rebuild for $170 and came back with exactly the same 
problem!

Thoughts?

Rich Chrysler