No, do not polish them. They have a special very slightly grooved surface where they make contact with the carb cap that is very precise and makes the nearly airtight seal that is necessary for them to work. Remember these don't have diaphragms. If you polish it, you could destroy the surface finish and you could loose your seal. If your slides are too dirty/corroded to clean, you may just have to find some nicer ones.
One problem I have had is with the carb cap alignment being slightly off and the slide not moving up and down smoothly. So now when I put those caps back together, I just barely tighten the cap screws and then check the slide motion. Sometimes I have to tap on the cap to move it slightly. Once the slide moves freely, I tighten the screws and check again.
Spotty, these are vacuum operated carbs. The cables don't attach to the slides.