So you didn't really address my 2 points, can you spin both disks by hand?
If yes, does spinning the speedo side disk cause the needle to move? If no that's your problem.
If yes, does spinning the cable side disk cause the part that receives the throttle cable to spin? If no, that's your problem.
If yes to both, make sure they are mated together tight and spin a speedo cable in a drill attached to the speedo to confirm needle moves.