I tried lots of special "tools" and decided I didn't want to damage the LHS case bore. But by then I'd buggered up the lower bearing trying all these ideas. I went to several dealers to see if they had a factory tool. Several said they did, but when it got down to asking the mechanic, he had nothing. One shop said they put a torch on the case and heat the cr@p out of it until they can drag the lower bearing out somehow. I quickly snatched my case half back from that guy and said "no thanks".
I ened up going to M.C.E. racing in Vista. Kevin has a KX500 and did a great job extracting the bearing, pressing in a new one, and fixing my cracked drain plug boss.
http://www.mce-racing.com/I realize this doesn't help you much as it was OOF (out of frame), but clearly a bad design by Kawasaki maintenance-wise. I think the trans oil lubes through the pushrod acesss area (not much).
Barry