I cut through the rubber using a two handed
wire saw (fed through the gap then handles affixed). You can then easily remove the metal outer housing. Clean up the arm and lubricate from the bush to the rear of the arm, then, using a hammer and drift (or hardwood peg) directly on the metal inner, work around the inner bush in a circular fashion. If this fails, hacksaw or, with care not to damage the arm, grind off the metal bush. The other side came off by hammer and drift alone. If you push the front wheel forwards slightly, you can wiggle the bush off the end. I did mine with the wheels on and on ramps.
Tools:-
