speedometer running fast

[jtparker]

I have a 2006 Yamaha F225. The Yamaha digital speedometer was working last fall but just put the boat in the water and the speedometer is displaying about double the speed of the gps. I removed the lower unit during the winter to have the seals replaced. I checked the speedometer tube at that time and it was clear. Any ideas as to what could cause this problem?

Thanks!