Speedometer is running fast

[gt69mach1 10]

Hi all, 69 mach1 speedometer is reading over 100 mph when going 50,60. and when I am stopped it does not go back to zero. Any ideas what I could do or try to fix this, or where I can get it repaired:confused:

[Midlife 814]

The speedometer assembly uses magnets and rotating shafts. If debris gets caught up in the area where the inside of the speedo where the needle rotates, the needle will get caught and not read correctly. This often happens when water gets into the speedometer assembly and rusts develops.