For this procedure the grating has to be removed first. The 3,mm AF hex ball driver kept with the gratings should be used to loosen the three captive screws holding the grating base in place on the turntable. The grating may have to be rotated to gain access to the screws. Before rotating the grating, release the clamp nut (anti-clockwise rotation) by half a turn. This brass knurled nut is located on the rotation axis outside of the instrument. Each grating assembly should be held by the handle or base and not by the grating cell.
The shutter mechanism can be pulled away from the slit by holding onto the body of the mechanism NOT the shutter blade. The mechanism hinges about the end remote from the slit.
The dekker should be pulled to the fully out position. The two toggle clamps located at the edges of the slit assembly should be loosened (anti-clockwise rotation) whilst holding the assembly. The assembly can then be removed by rotating about 30which releases the dekker control from the slide bar.
Mounting is the same procedure in reverse and the whole operation should become more obvious when the hardware is inspected. Before tightening (lightly) the toggle clamps ensure that the new slit is rotated anticlockwise against the rotation stop and that the dekker slide and control rod are correctly engaged. Check dekker and shutter operation.