resto of thumbwheel wheel?

[roadrunninmark]

How can I brighten up the thumbwheels on my old radio?  Do they need to be rechromed only?  What is the safest way to remove them from the radio, without any surprise parts flying off when I remove the screws (as I haven't taken them off before)?  I am hoping they just turn some fixed gears behind them and nothing is spring loaded on the inside.