there are two harnesses inside the gauge cluster...maybe one of them is unplugged

 

I didn't even think about that but the same thing happened to another member a few weeks back. Check out all the connectors first but I'll almost bet that this is it

 

it was exactly that, i narrowed it down to a bad cluster, then took it apart and found those harnesses. but the tach still didnt sweep, for some reason it was too tight against the face of the gauges, i took it off and put a little pastic washer in there, all is well now everything works the way it should

 

just got her legal today, not enough time to finish buttoning things up, but shell be out after i get off work in the am! so excited

 

I'm glad to know that you were able to find and solve your issue!