mechanical speedo problem
 

so i have swapped an sr5 cluster into my truck, and the speedo does not work correctly. at first it did not work at all. then, i tore apart the old cluster and put that speedo into the sr5 cluster. it registers speed, just extremely low. what is the problem? can you actually damage a mechanical speedo? please help so i don't have to pay $400 dollars for someone else to fix this.

anybody?

They are magnetic and if they get whacked pretty bad they can lose the delicate balance they need to build up the magnetic friction. This is not something I know alot about, just inferring from talking to a speedometer repair guy.

It could be that something like a platic gear is stripped, Maybe iven in the transmission connector.