If your speedometer is not working, you have came to the right place
Below is a pic of what connects the flexible metal speedometer cable to the speedometer gauge. What happens is the plastic tube on the right cracks and doesn't couple to the metal speedometer cable. Clean it well with brake clean and let dry.
Here is a pic of the outer housing of the speedometer cable. It is spring loaded and rests inside a notch.
Looking into the speedometer cable housing, the cable is terminated with a round cylinder. Clean by pushing a paper towel down into the cable housing and rotate. Once clean, apply a dab of 5 minute epoxy onto the tip of the round cylinder. Be careful so that epoxy winds up on the tip of the cable and not on the housing. Next put the spring into the plastic tube and press the plastic tube so that it goes over the round cylinder in the speedometer cable housimg. Apply pressure for 5 minutes so the epoxy sets up.
Reinstall the dash gauges and confirm that the speedometer works.