You should not refinish
Brake Drums in an attempt, inspect each of the brake drums and determine, use the J 41013 to thoroughly clean any corrosion/rust from the brake drum flange, mount the brake drum to the brake lathe, ensure that any vibration dampening attachments are securely in place, bring in the cutting tool, observe the witness mark on the brake drum, inspect the brake drum diameter, remove the brake drum from the brake lathe and then use the J 42450-A.