Should piston gudgeon pin retainers be replaced at rebuild?

If there is a flat side make sure its' facing out.
If you are not removing the pin from the pistons, leave them alone, if removing the piston pin........?!?
Yes, replace them cheap insurance, open end of the criclip up toward the top of the piston. Try to only use your fingers to install or a wooden dowel, no screwdrivers, no metal scribe, or awl.