If your going to completely disassemble the machine to repaint it the best way to remove the bumpers is to take the tank and soak it in very hot water, this will soften the bumpers and you can pull the bumpers toward the front, and once they unhook from the metal rail just peel them off the side of the machine, when you reassemble them  soak them in hot water and from the back of the tank forward slide them on the metal rail and when you get to the front pull them past the metal rail and slide them over the front. It sounds harder then it really is, it is very simple to do. Good luck, I would love to see the machine after you paint it, take some pictures of it. I have a Diamond Jubilee that I put a Miele motor in and painted the body with Gray hammertone paint that I use out in the garage to vacuum out the cars, the machine is a beast, no factory Electrolux has the suction that this machine has, and it looks pretty cool too.