This may be helpful. A very annoying cyclic clicking from rear brake drum when slowing to stop or breaking at about 5mph. I thought it may have been slight eccentricity of drum because of cyclic nature. However seems to be fixed by new slave cylinders, old ones had severely distorted bent metal tabs fitted to the ends of the pistons, the purpose being I think to hold the shoes in place against the back plate. I'm guessing they bent when pulling the drum off. Not sure how to prevent it happening again at garage or something, any ideas welcome. Rich.