Hi Adam,
Each side of the cooker you have a gimbal mounting that consists of two distinctly separate pieces, one of these is securely fastened to each side of the cooker, while the other part is attached the sides of the opening in your galley furniture. The part attached to the furniture consists of two pieces of stainless steel that are spot welded together, and it is this part of the mounting that I'm going to discuss with you. The part of it which is nearest the cooker is made of the thicker of the two pieces of stainless, while the part nearer to the woodwork is thinner. The weight of your cooker is carried by the thicker part, while the thinner part will, when the cooker is lowered into place, spring back over the ends of the trunnions on that part of the mounting that is attached directly to the cooker. The reason for this is to prevent the cooker from becoming detached from its mounting in the event of a knockdown while out sailing. To get the cooker out of its mounting, you need to prise the thinner piece of steel away from the thicker part at its top edge, and this will then allow the trunnions to slide out as the cooker is lifted. The mounting bracket attached to your furniture will remain in place, while the cooker and the trunnion mountings then lift free. Be aware that the gas hose behind the cooker is of limited length such that once lifted free from the gimbal mount that you may need to lower the cooker onto the base of the cut out in your furniture in order to release the hose (don't forget to turn off the gas before you do this). While the cooker is out, this is a good opportunity to check the gas hose for any wear. I can't remember the recommendation, but I think it has been suggested elsewhere that these should be replaced every five years. Mine was a lot older, nearer to fifteen years and was very badly worn where it rubbed against the inside of the hull while gimballing at sea.