'63 Saginaw speedo trouble

[aboz]

I can't get the speedometer to work on my '63 Chevy stepside. I started with the simplest step by replacing the cable...no go. I tried three different size plastic driven gears before noticing the drive gear's threads were nearly rusted away. I then rebuilt the 3 speed Saginaw myself and replaced the steel drive gear but still can't get it to work. I then removed and the speedometer, tore it down to check for any worn or broken parts and put it back together...an occasional bouncing speedo needle, then nothing! The only thing I can figure is when I slid the heated drive gear back onto the shaft exactly where it was before, the placement was slightly incorrect to begin with although I have disconnected the cable from the speedometer and watched it spin as I drive. Can anyone offer me any advise?