Dust blast them if you feel its necessary. I wash mine in solvent with a scotch brite pad and they look good unless really warped or burned. Theres 21 of them so failure isnt likely.
While its apart, measure the spring length and inspect the retaining cup and pin and replace if needed. If its a 26-7 brake drum, replace the lugs; they just snap in. Follow the book on adjusting the 3 release arms for a decent neutral adjustment. ws