Most of the old Schwinn hubs I've came across (Normandy) have removable metal dust covers that press in over/around the bearing races. I usually use a plastic tire lever or a stick of wood and pry them out VERY CAREFULLY, working around the diameter slowly and with light pressure. Be careful though, because they will bend easily if you do some gorilla-esque prying with a metal screwdriver. Once the little metal caps are off, access to the race for cleaning is a breeze, and the bearings go back in easily. I usually press the cover back on after I've got all the balls back in the race and the grease is holding them in place.