Those pedals aren't really made to be serviced, but it is possible. You need to grind off the mushroomed end of the pins that hold the rubber blocks in place. That will allow the end plates to be removed from the pedals so you can service the bearings. If there is still enough left of the pins, you can reuse them by flaring them with a ballpeen hammer, or you can get some #10-32 all-thread and some acorn nuts to replace the pins.