I had new instrument panel with wiring harness installed with new SS reproduction gauges. The cars speedo does not work. All the other gauges work great. I am not a tech savy guy I just don't want to tear the dash apart and end up with a mess that I can't fix. Can anyone tell me what to do? I would take it back to the guys who did the work however that's about 1500 miles away now. thanks for any help

1970 Chevelle I assume?
The most likely thing to check would be the cable connection on the back of the speedometer, since it was recently installed, I would think.

Might have to remove the dash pad for easy access. :(