I've been given a pair of Shimano PD-R540 pedals. They're usable, although there's play in the bearings. I've stripped one down, cleaned, greased and reassembled but can't get rid of the play. They're built with a spindle/bearing cartridge in one piece which makes me think they're meant to be replaceable, but I can't find anywhere that sells them. What do we do these days, just bin 'em and buy new pedals?