[Dan in Pasadena]

The speedo on my '76 has begun behaving oddly. I noticed yesterday that at a good rate of speed on the freeway; say 80mph or slightly higher, it was registering 45 mph. It wasn't erratic, just slow. It DOES return to zero at stops. At a lower rate of speed it is still off, say 30-35 when I am in fact traveling at about 55-60.

I am thinking it is the gauge itself and am wondering if there is anything I can DIY? Or is this an expensive, "Send-it-to-North-Hollywood-Speedometer" fix only? Anyone have any experience with this?