Clocks

Hi

The speedo on my Mk1 Cab hasn't worked since I had her.  We have replaced the speedo cable but still nothing.  We tried using a drill on the speedo cable but still nothing on the actual speedo.  Do I presume from this that the speedo clock has gone and possibly not an issue with the cable going into the gearbox?  If so, how difficult is it to change them and do any other golf clocks fit?

Thanks

What bit of the speedo does not work, do the miles count up?

Is the cable fitted properly to the back of the speedo?
Does the speedo end of the cable spin when you drive?