"Cy Galley" wrote in message
news:eAeid.52917$R05.12713@attbi_s53...
You can take it to an automotive speedometer shop and they can clean,
lubricate, and calibrate. Tell them that it is driven off the cam in your
stock car so they get it right and don't panic.

Okay, Cy - here's what I found out. The speedo shop said they would be happy
to look at it and fix it, even if they have to throw away the guts and
replace them with a new SW unit. If they have the parts, it would be $92 for
an overhaul. A completely new unit would run ~$120.

They said the common problem with this type of tach is worn bearings on the
cup shaft which allows interference between the cable shaft and the cup. The
scuff marks in my tach make it appear as if this is the problem.

I think I'll buy another used but operative unit. Prices seem to run in the
$40-60 range. If it lasts another three years I'll be happy.

Rich