Best guess. The cable used is some of corvettes had plastic ends. To fit into plastic parts. More than likely. The reason for the binding on cable was poor lube from the manufacture. Basical the end of the connection was twisted off. No connection. Lubing will not fix the problem. Also make sure that the cable did not damage the speedo connection. You may find a broken connection from the cable still inside the speedo. But be careful of the printed circuit plastic on the back of the panel. Good luck!
I own a 1978 Corvette Pace Car that has 69170 miles on it. The speedometer has stopped and the cruise control won't engage. Both speedo cables are good. If I disconnect the cable from the side of the automatic transmission and try to turn it by hand, it binds up & won't turn. The question is should the cable and cruise control transduce turn freely when turned by hand. It appears that it may be jammed. Can it be taken apart and lubricated?