Honda Repair: tach jumping or dead, digital multimeter, delsol

Question
I have a 93 delsol Si and recently the tach started jumping all over erratically and now is mostly just at 0 rpm.  the car seems to run fine, no stuttering or poor performance, or check engine light, the tach just sits there 95% of the time at 0 and occasionally jumps all over the place, then goes back to 0.  so far I pulled the cluster and checked for lose connections behind it.  they were all fine.  and I wiggled the wires on the distributor while someone watched the tach and it just stayed at 0.
I think in these cars the tach speed comes from a sensor in the distributor correct?  I have a digital multimeter if there's anything I can test.
please let me know.
thank you for your time and expertise.

Answer
Mark, quite possible the cluster is just worn out and tired. There is a speed sensor on top of the transmission but that controls MPH's. At first i was thinking loose connection too, but, you checked that already. Is there a fuse for it? I think but not 100% - TACH - 10amp fuse if there is one. Other than some trial and error and/or cutting and splicing some wires i would replace the instrument cluster completely. Check Ebay and there are some cool JDM (Japenese Domsetic Market) units out there too. When searching for Del Sol's on the JDM market they are still classified as CR-X's.