speedo

[FH1]

hi , i have a little problem with my 99 a4 tdi, the speedo needle is sticky and the mileage display is playing up (sometimes it will show full display and others itll only show some digits,
i have rang a couple of breakers and sourced a set of clocks now im told they may need to be chippedto match my key,
could someone please shed some light on this for me
many thanks