Speedometer issues

So for quite some time I had a jumpy, loud, rattling, speedo. Having finally looked into it o was convinced/dreading that I totally blew the thing up, but low and behold I gave the cable a lube job anyways and it solved almost all my problems. I say almost, because now my speedo is a constant 12 mph high. 12 @ 0, 52 @ 40, etc. It also seems (and this could just be my perception) that it isnt falling accurately.

I was just going to disconnect the cable and see about turning it down by hand, but I REALLY dont want to incur the cost of replacing or rebuilding it, so I figured I'd ask you guys

Thanks as always,
Futzy