Speedo help.... opinions?

[brads70]

I just installed a new to me gauge cluster( after my speedo needle went south after I swapped it out for another needle) that I got off e-bay from sniff out parts.  All went well but the speedo is out? It is about 20 MPH out ...BUT?? the odometer is perfect?     How can this be? I took it out for what maybe it's last run of the season, noticed the speedo right away, but the odometer seemed right. So when I came home I used google maps to retrace my route and the mileage was exactly the same as the odometer. ( One tenth of a mile out) I know the speedo and odometer are geared together so if one is out they both should be?
The e-bay vendor has been great and he can't figure it out either?
Any idea's?

[Chryco Psycho]

the speedo needle is just moved with a spinning magnet not a direct link / gear like the odometer so the needle is overly reactive to the spinning magnet .

[brads70]

the speedo needle is just moved with a spinning magnet not a direct link / gear like the odometer so the needle is overly reactive to the spinning magnet .

So in my case it's not reacive enough? ( speedo reading too slow)
any idea's how to fix this?

[Chryco Psycho]

clean & lube it , make sure the magnet is close enough to the drum