[Mk2] [Turbo] Speedo problem

[SUBO2356]

Hi My speedo (1992 turbo) has gone faulty, all bouncy and reading slow
changed the nylon cog---stopped bouncing
changed the speed sensor(reads in mph) and removed kph to mph thing----seems to work fine but after 20 miles it reads slow by about 50%.

what i want to try is to replace the electrical connector onto the speed sensor and rewire it to the back of the speedo.

is this possible and does anyone have the wiring diagram???

cheers AJS