70 Rally speedometer issue

[Dirtygunn]

I recently changed out my ring and pinion gears so I knew I would have to change out my speedo gear, before this the speedo worked fine, so after everything was done I took it out for a test drive and it was working fine for about a mile then the needle started jumping around and now when I just creep forward it will slowly move up to 50 mph and when I roll a little more it drops back to 0, full disclosure this cable and speedo haven't been used in 20yrs.
Is this just a lubrication issue? Or is the new speedo gear the problem, I know I clocked the gear correctly as I've double and triple checked
I'm hoping my speedo isn't F#@$ed, I haven't driven again as I don't want to trash anything
Any helpful advice will be greatly appreciated
Thanks

 

[493 Mike]

Did you lube the cable? Pull it out from the top, inspect, and lube if you haven't. Retest.
Mike

 

[dadsbee]

Take it off the transmission. Attach the cable to a cordless drill and run it in REVERSE!