I had a similar problem with the Speedo cable in my 50.

https://www.stovebolt.com/ubbthreads/ubbthreads.php?ubb=showflat&topic=103931&gonew=1

Turns out the square drive shaft on the cable was to long

went to CARQUEST and got this cable
...pic...

Took care of the problem I had.
the replacement cable is black vinyl
Good Luck