Speedometer Trouble

The one I have (stock square 120mph) I believe uses magnets. It has 2 "fingers" that rotate around a metal cup that connects to the needle and as the fingers spin it counteracts the slight spring tension on the cup and swings the needle. If there is anything in between the fingers and the cup it will cause the needle to jump up then fall as they come in contact with each other. This seems to come up enough.... I'll snap a pic of a speedo that is sitting on the shelf in the garage and try to post tonight.

Now, the speedo of unknown origin????? might work by PFM.. :lol: the gear ratio might be way off, but you should be able to spin it with a drill to see if it's ok internally