Speedo Needle Sticking

[munia]

Hi All - I hope someone can help with a problem thats been ongoing for about 6 months - whenever I travel between 60mph - 70mph the needle on the speedo seems to get stuck around the 60mph mark then jumps to 70mph when I reach that speed, its not smooth as you would expect and only seems to happen at motorway speeds - anyone had this problem? where should I start looking before taking in to VW to be told I need a new dash, speedo, cables, wheels, engine etc

Thanks in advance