I have the exact same problem with my 1996 Maxima. The speedometer will suddenly just zero out on me for a few minutes at a time and all of the sudden will come back on and everything will function properly. I have also attempted to check the continuity of the voltage flow and have become stuck at the same problem: is the problem the whole instrument panel cluster or can something be salvaged. If you have found a solution, please let me know. I will do the same.