I wonder if you could take them out hydraulically like you can remove a clutch pilot bushing (on a car)? Pack the bottom of the hole with grease, and drive/press a slip-fit slug into the grease. Pressure differential caused by the different surface areas multiplies the force and pushes out the bearing... Heat first couldn't hurt. I don't know. Maybe worth a try. I've used it a couple times on blind fit plane bushings.