Speedo is flickering and jumping especially above 50mph!!

Hello

I bought my mum a VW MK 1 cabriolet. I know a bit about cars, but not much at all about golfs so please help me out.
It is a 1.8, K Reg Clipper with the karmann badge on the side if that helps to identify it.

Now the speedo cable in the engine bay is white and looks pretty new. I wonder if this was replaced due to an ongoing fault with the speedo or not but i dont know.

At all speeds really the speedo jumps and flickers but this problem seems to come and go, approx every 15mins it will do it. However at a higher speed of 50mph + it does it a lot more frequently.

eg the speedo will be reading 60mph then it will jump very quickly to eg 100mph and drop back down.

Its done this so often that the speedo needly actually broke off the other day.

Is this a common problem? whats the solution? If I dont get this fixed in time is this somethign that will fail an MOT?

Thanks a lot guys

Is this a common problem? whats the solution? If I dont get this fixed in time is this somethign that will fail an MOT?

It is quite common , but will not affect the MOT .

You will have to replace the speedo head if the cable and plastic cog in the gearbox are sound .

I had this problem years ago and a 2nd hand speedo head cured it .

Great. thanks for the reply.

When you say replace the speedo 'head' what is this? Is this the main speedo clock and the gadgetry behind it, or is it like a separate piece that attaches to the main clock that can just be replaced?

thanks

Is this the main speedo clock and the gadgetry behind it

Yes mate , its a complete unit

OK thanks.

Now potentially buying a 2nd hand one will also have the same problem, but i guess also they may not sell them new anymore.

In terms of buying a 2nd hand one are there particular years and models i should look out for. Mine is a K reg 1.8L karmann clipper, but i know they made a 1.6L version too so the clock may be different.

Is the same clock used in the mk II's?

cheers for your help