When I replaced my broken gear packs, I used a bottle jack at the outer end of the square tube, with the slide extended, and with the small distance you will need to move the slide, you should have enough movement available. I put the bottle jack on the ground and use a timber up to the tube. I’m actually using my Safejack kit with the extension pipes to reach the square tube, but not everybody has them, so that is why I’m suggesting using a sturdy piece of wood.
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