I'd say that a rebuild OUGHT to put the gauge back to as close to original
fuinctioning condition as possible. The tach wavering might not be
coming from the tach unit. It might be the cable or binding between the
cable and the tach.
I can't tell what is wrong with your trip odometer from what you said.
Why won't it zero? Do the wheels not move when you turn the reset knob?
What year and model is your car.
Check out my speedo repair manual at:
Message text written by INTERNET:firstname.lastname@example.org
>From: "Tom Winslow" <email@example.com>
A local British car repair shop sent my JAEGER tach and Speedo out to be
rebuilt. The cost for both was about $275. I still have the same problem
that I had before the rebuild. The tach will be rock solid for a while and
then it will start jumping + or - 500 rpm - like one of those drinking
birds. The only problem that I had with the speedo was that the trip
odometer would not reset. Once the rebuild was installed, it reset one
time - and now it will no longer reset.
Should these instruments function as new once they are properly rebuilt? I
am not sure what I should expect.