Speedometer troubleshooting help

[sovapid]

This is for a 72 4wd Blazer, 4 speed, and np 205 transfer case.

The PO told me the speedometer cable was bad. So I picked up a new one and replaced it today without doing any trouble shooting to make sure it actually was the cable.

Well, got it replaced and it still doesn't work.

If I'm going fast enough, the speedo will bounce around a little bit. It never actually holds any speed, but it does move.

I took the speedo cable off the transfer case and spun the cable. The speedo did move.

So I figure it is something down on the speedo gear at the transfer case.

After some searching I found this thread:

http://67-72chevytrucks.com/vboard/s....php?p=2998056

This doesn't really look the gears on these things are going to wear out/break like the newer plastic ones.

What should I be looking for?

Maybe the gear is rounded out where the cable goes into it?

Can you buy new speedo gears for these?

Thanks

Sean