So I did a little research on this already, but literally the day after I bought my '56 Coronet a few weeks ago, I was on my maiden "hometown" voyage when the speedometer started to buzz. It had chattered just a tad on my test-drive before buying it, and the seller mentioned that it had just started doing that.

Well, I took it out last weekened for an actual cruise, and oh my GOD it was screaming at me by the time I got it home.

From what I've learned, it's either the cable or the speedometer gauge itself. I've read that you can disconnect the cable and see if it still does it - if so it's the cable, if not it's the speedo.

My question is, if it's the speedo, what are some likely culprits/fixes? I've read that some cars need a drop of 3-in-1 oil, some need a graphite-based dry lubricant, and some simply need rebuilt. In the case of the latter, does anyone have any recommended vendors that can restore these gauges?

Last question: any tips on removing the speedometer itself without tearing out the entire dash? I can see the back of the unit from under the dash, but I haven't started reaching up there yet. (When I do, I'm going to disconnect the battery first just to make sure there isn't any wiring up there that might have cracked/worn insulation and short out...)