Hi Brian, when my '57 speedo started screeching it was very apparent that the noise was from the speedometer itself, the needle was erratic as is your unit. I had lubed the cable prior to the noise and I knew it was probably not a cable issue. Warm weather driving didn't present a problem but in cold weather it would squeal. I removed the speedo and cleaned it and made sure to oil the rear most bushing, that is the input where the cable slips in, the bronze/brass bushing needed oil, I used something light weight, gun oil or clock oil, have not had any more noise and the needle runs smooth.
