The cylinder is often stuck to the case and studs due to 30-40 years of rust. Using a thick steel plate with holes for attaching the cylider might solve the issue

Screw down the bolts down onto the studs who are connected to the case.

fasten the steel plate to the cylinder with screws

Gently screw the bolts one at a time, little by little until you have a “lift off” and the cylinder is loose.

Note: Remove the nut underneath the intake in the middle (right hand side of the tube). I didn’t and ruined the cylinder. Luckily I got hold of a new and better cylinder.

Lesson learned: Build yourself a man cave with better lighting and more space.