I know others will chime in, but I had excellent service and quality of repair from Palo Alto Speedometer.
You may not need to replace the speedo cable, you can pull it out, and soak it with cleaner/degreaser and relube and it may be fine. It could also be contributing to the dial jumping around.
The glass is cleanable and a number of folks on the site have done that. It does require a careful removal of the chrome bezel.
You should be able to use the search function and find some info about the lights. I don't remember off hand how many there are.