02 scrambler 500 4×4 ,question about 4×4

so I just got a 02 scrambler 500 4×4 so I am new to these bikes I have pulled the front wheel and hub off. if I understand correctly there is to be oil in the hub not grease?
there is a part called a armature plate flat washer with 3 small tabs, with the switch in the on postion this plate should hold in place (should bike be running) I need to replace these mine seem to be warped I assume they should be flat.
I have a wheels off ground and the bike appears to be in 4 wheel drive nothing seems to happen when I flip the switch also is there a indicator light the says its in 4×4