Passerelle - new wheels

[KBD]

I need to change the old rubber wheels on my passerelle for plastic ones. I have removed the outer nuts on the spindle. I Preseume I have to take off one the the end pieces holding the spindle before I can take it out and replace the wheels. The passerelle is Italian made by Besenzoni. From what I can see the end pieces are held on by three phillips S/S screws, one on top two underneath The gangway is alluminium and I can't undo the screws which may have bonded. Any ideas gratefully received.