The dremel with a proper brush isn't dangerous, you basically can't screw stuff up with it (other than maybe bending some switches, but you should be checking and adjusted as needed when you go through the game anyway). It's not like it's a saw or something where one wrong move is gonna break stuff

First move on any Williams is to clean all the steppers, they're always gummed up. Take the plate off, polish the contacts on the board with metal polish. If necessary take the whole mech apart, cleaning it with alcohol to remove the grease, until everything moves freely