I had success by sliding the shaft down a length of pipe with a washer big enough to protect the dogs, had some kind of fastener with a big enough head and a washer to protect the shaft end(with nut on), used a 10Lb hammer on a lump of hardwood to drift it. The pipe was a bit long, so stuffed some rag up the bottom to cushion it if/when it popped off- seemed to go easy enough
Much the same concept in reverse to add the replacement