[Tallguy]

I've read a few posts about speedo issues, indeed my rotor has failed once before and was replaced.

I had new tyres fitted a few weeks back and the speedo issue happened, I figured it was the rotor damaged by the fitter, same as last time.

However, my mechanic (Alan Lear of Winchester) stripped it down and he says the rotor looks like new, so he cleaned it all and put it back together again.

It seemed to work for a while (days) but now it's back to occasionally-correct but mostly-random numbers. It seems to be worse in hot/harder riding.

Alan Lear says that it's more likely the speedo drive than the rotor, based on his assessment of it last week.

Can anyone provide some info about this? E.g. if I searched on The Bay of E, could I look for speedo drives for SV650 K3 onwards or would only certain ones work? Would (say) GSX or other speedo drives work? Can the existing rotor look OK but actually have failed invisibly? Or could it be something else of which I'm ignorant?

Thank you, o mighty Org, I supplicate myself at your (cheesy) feet.