Speedometer Question

Same thing in my 65 Newport. It was a worn bore in the aluminum housing that the magnet yoke spins in. I sent the part to a speedometer shop in Bakersfield and they installed a bronze bushing. If you don't fix it, the yoke will eventually grab the aluminum cup, which hopefully just breaks the cable (my case). Of course, it could just be a grabby cable as mentioned. I haven't looked at a Dart speedo to compare, but my Aries had a similar problem (cracked plastic yoke).