Is there much wear in the bushings? I used to always replace the whole bushing and Deere used to have a shim kit to cut down on the side to side movement. Even the pliers made for those rings would put a kink in them. The times I tried heating them up, I wound up ruining them. Good luck to you.
Later models went to an external piston to control the rock shaft. I understand your frustration. I can't stand an oil leak either. If I remember correctly there was an o-ring under the packing. I had a 4040 that was leaking between the bushing and the packing. I found a teflon back-up o-ring from Parker Hydraulics that stopped it. Hope that helps.
Try soaking the seals in hot water. I have found that it makes them more flexible and easier to install. Also you may need to replace the pin and bushing at the front of the load control shaft bracket. Good John Deere parts, replacing the pin and bushing, and keeping my pull arms tied together when not using a 3pt implement has ended my load control shaft leak problems.