Here are notes I made several years ago after replacing outer axle bearing on my 51 8N
1. Remove axle 2. Put new bearing cup (race) in the freezer at least overnight 3. Pressed old bearing off axle with Harbor Freight 12 ton press. Leave nut on with outer threads flush with end of shaft. Came off easy 4. Remove oil seal from race holder 5. Weld bead around inside of race at about middle of race. When I took screw driver to brush out slag flecks the race turned so a couple of taps with punch drove it out. 6. While race holder was still warm I took frozen race, applied a thin film of oil and, using a block of wood, tapped the race into the holder. 7. Put new bearing in a pan of 5w-30 motor oil covering bearing. Put on burner and let heat until oil smoked. I continually stirred the bearing around in the pan with a wooden dowel. (get it out of the house as soon as it begins to smoke!!) 8. I had shaft, old bearing and pipe sleeve ready to drive new bearing on to shaft. I removed hot bearing from oil, dropped on shaft and it dropped completely on, no driving necessary.