to clean them i use a needle to pick the retaining ring off from the outside rim, same with rubber sealed bearings.
clean dirt off the shields with a tissue dipped in motor spray. for the bearing i flush the dirt out from one side only to prevent them from getting back in. if u have bearings that has the brace on the one side instead of the center(whre u can see the balls from both sides), flush it from that side(hope u know what i mean). then i just add a drop of Trinity oil and put them back together. for rubber sheilds, if they deform from dissassembly, i just flatten them with the end of a wrench/driver on a peice of glass. metal sheeilds may not always sit in place,when the retainer is in, hold the inside rim and "push, roll and wiggle" the outer ring till theres enough clearance between the sheilds and the inside rim.
hope this helps.