browning gear can help with sprockets,gears and chains. something tells me when they built them they tried to use off the shelf items. a good bearing supplier should be able to help with seals. as long as the keyways are ok the shafts could be reused. when i worked at the mill we used J.B. weld on the shafts where the seals rode and it worked fine. they have much better epoxy these days that would work.
