all the original ones i pulled apart and cleaned had three distinct shallow waves in the wire near the knob to induce friction to give them a bit of holding resistance against the carburetor springs, these waves are a couple inches spaced and extend a half foot or so down the wire from the knob.
when you are cleaning the wire and removing the bad kinks consider that if you make it perfectly straight and smooth you will end up with the opposite problem.
when i'm driving through the field or on rough roads, the cables always vibrate back in because the return springs are so strong, i would need that "two feet on the dash" tension to keep them from moving back in
i figure these knobs are only for stationary application like keeping the engine running on a cold start,
the throttle knob probably could never have been used as a cruise control, it would have worked it's way towards the dash with vibration even when new,
there are after market cables from the 50s to replace the OEM ones that would slide in on their own. they have a locking lever device so they stay put, and you can make fine adjustment by screwing the knob in or out, or you can override the holding clamp at any position and force it over the spring loaded detents
one of my 2 Ton's has this kind of knob in it, much better than the original, something to look for at the wrecking yard next time your there.
-s
