Gearbox Speedo Linkage HELP!!!

[mudra]

Hi Guys wondering can anyone help me out I have a GSI nova 1992 and the speedo hasnt worked on it since I bought it of a guy. I have taken all out changed speedo cable, the dash is working fine with a drill and have it narrowed down to the linkage on top of the gearbox. Does anyone know if this give any bother and can this be replaced.
Thanks in advance

[mowgli]

the plastic gear can snap or sieze inside the gearbox. its easy enough to swap.