shows a Compur MXV CN-1110-543 shutter which is an adaptation of the CS-1110-020 shutter, the 543 variant is not shown. Lens cells screw into the shutter from the front and rear. Once a cell is removed from the shutter then it can be disassembled into its component parts.

Use a rubber sink stopper that just fits the inside of the lens opening without touching the lens itself. While pressing down hard turn the stopper counterclockwise. Lens become stuck with age and are sometimes difficult to remove. You may need special tools to open the front cell once removed from the shutter to access the space between the two front elements. Spacing between the two elements is critical.