The entire speedo system works fine in warm weather, except the needle bounces a wee bit.

I had forgot it doesn't like the cold.

Since I owned it, in the coldest months the speedo, from time to time would make a loud, vibrating, gear chattery rotational noise. And it causes the needle to bounce 10mph indicated worth either way of actual speed.

When the interior of the vehicle would warm up it would stop at least for the 1st winter or two I drove it.

Meanwhile back at the ranch, It was pretty bad last winter. Sometimes the speedo would make a heck of a chatter and the needle would max out past 100 indicated mph. It eventually broke the needle.

Again come warm weather last spring it went away.

I had forgot about the issue but it did it's chattering thing for just a moment this am.

So, anybody know what exactly causes this and how to fix it right off the bat? Or a strong suspicion of what I should tear into/replace first?

Thanks!