Hi,

Just thought I would put in a word to match up with Arts information on how the needle moves.
The newer electronic speedometers are a mixed bag of old and new technology.
Here is what I found on my quick and little of effort research.

I put in a search for how the Eddy Current speedometers worked.
https://auto.howstuffworks.com/car-driving-safety/safety-regulatory-devices/speedometer3.htm

I learned about this a long time ago, because on my bicycles I had two speedometers wear out and gleamed one more learning lesson of value from them before throwing it away.
I hit a puzzle for sure as I was curious of how does a spinning magnet turning under an aluminum cup every work and back then if you were curious in those days,, you had to go to a library!

After you read this link, the rest is up to imagination.
I know if you have seen swirls of water in a river. Just put that inside the aluminum cups walls and it will help identify magnetic fields being, temporarily held, in that type of mechanization.

The article above fits into what Art is saying about current coming as it’s signal driven and hanging on to the same analog sensory output for us.

I hope this fills in that I would change any capacitor in a circuit that is having issues.
Especially, when things are intermittent!
They are the oldest technology left in there and they fail in some of the weirdest ways!
To backup that thought, the ones in that speedometer are made with rolled up aluminum foil!

Phil