Rallye speedo stuck on 20

[midnightrider1818]

Took my 73 roadrunner for a drive today and noticed my speedo was stuck at 20, it moves up and down but won't come back down below 20, seems to be 20 mph off also, I took the speedo cable loose off tranny and spun cable and no binding and spins free just still stuck at 20, has to be internal in the speedo, first time I have ever ran I to this

 

[Sinitro]

If U pulled out the cable and still the needle is stuck..
Speedo needs to come out, likely needs overhaul and lube..

Just my $0.02...