Speedo drive

Hi,
I have been experiencing problems with my speedo on my '01 650 (Curvy). At high speeds it's almost 40 MPH out! Recently my Husband was following me on his Gixer at 130 MPH, my speedo was reading 95 MPH, i was really shocked!

I took my bike to the local Suzuki dealership to have them look at it, but they couldn't actually find anything wrong with it except that "it's a problem with the speedo" (No **** Sherlock!) They narrowed it down to either being the speedo head or the speedo drive, which is fairly obvious as thats pretty much the only parts to it except the wire inbetween!

Anyway. has anybody else experienced this problem and does anybody know if the speedo drive from a new SV650 is the same as the old model as there is one on ebay at the mo and it's a hell of a lot cheaper than a new one.

Any advice much appreciated

Carly