Barry I have a lot of the same problems your having. The way I understand it while face or edge jointing you need to press more on the rear part of the board then when it gets about half way across the cutter head press more on the front of the board and very little if any on the rear. I do this but still have problems. One thing that would help us both is to get helical cutter heads for our jointer and thickness planer. The problem is cost ( they ain't cheap ). I have heard that the best things in life are free but that doesn't apply to wood working.
PS- This is the reason I buy straight run lumber that is 13/16" thick. I was trying to edge joint a piece of hard maple yesterday that was 20" long. It had a slight bow on the edge with the two ends being high. I could never get it dead flat so I took it to the table saw and ripped the other side turned it around and ripped the bow out and then squared up both ends. There is some really good wood workers here so maybe they will help us out.
PS- This is the reason I buy straight run lumber that is 13/16" thick. I was trying to edge joint a piece of hard maple yesterday that was 20" long. It had a slight bow on the edge with the two ends being high. I could never get it dead flat so I took it to the table saw and ripped the other side turned it around and ripped the bow out and then squared up both ends. There is some really good wood workers here so maybe they will help us out.