Hi Donnie
I use a small wire wheel on a battery power drill, it is fast and effective. Wear a leather glove on the hand that holds the cable end being cleaned... this will save some skin when the wire wheel jumps up the wire. With a little practice you can get quite fast at this. Apply the dielectric grease to all sides during re- assembly.
You can disassemble the F&R by removing the center shaft. Apply dielectric lube to the rotary contacts and center shaft upon re-assembly for the smoothest operation possible, adjust the tension nut to ensure proper contact.
Inadequate contact pressure will allow arcing which may damage the contacts.
There will almost always be some amount of 'hard to shift' effort needed for this type of rotary contact switch.
I hope this helps
