The four screws on the front allow the shutter mechanism to be lifted out. The level used to prime the exposure has a small knob. This can be unscrewed before getting inside.

The 3 or 4 blades are held on to a ring by punching the thin plate into the hole. The other end is similarly punched with a hole. The sharp edges are then trapped into the four slots in the lens barrel. When the rim of the lens barrel is rotated these blades slide across the centre.

These blades are turn up slightly so that they can slide over one another. It is all too easy for them to miss and become dislodged. This can result in subsequent movement bending the loose blade.

 

The shutter has two blades and a neat mechanism to catch the second blade open when B has been selected. The instantaneous setting is dependant upon the spring on the outside, deepest into the camera.