There are numerous shops around the country that do instrument repairs. Here are a few:
http://www.paspeedo.com/ ,
http://www.continentalimports.com/ .
I am partial to the second because I own it, but the first is Top flite. I would have added United Speedometer but I didn't have their site or Nichol's Speedometer because they don't have a site. United is in Ca. and Nichol's is in N.Carolina. Numbers can be found if they are more convenient.
------------------
Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician