Speedo Cable Does Not Spin/Turn

"Back in the day" every single parts store that claimed to be one stocked universal cable repair kits. you cut them to length, crimped on the little square end, and went down the road........unless the insides of the cable jacket were torn up.

speedometer cable repair kit - Google Search
Yup I use to sell them. The brand I carried was in a green package and the name brand was Perfect Parts. Sold a bunch of them.