- open up the south cover of the instrument (it does not need to be fully removed, just opened enough to be able to access the brake)
- before changing the grating angle, slack off the 4 black bolts on the physical grating brake on the grating (inside the instrument ) to release the brake
- in the software, go to the ''Config'' tab, click the ''Unlock'' button, and enter the password
- still on the ''Config'' tab, click the ''Deactivate Grating Brake'' button (this will change to say ''Apply Grating Brake'')
- after the grating brake has been released in software, the initialise grating angle entry and the grating angle ''Go'' buttons will be enabled
- initialise the grating on the ''Advanced'' tab
- in the ''Main View'' tab, enter the required grating angle and click the ''Go'' button
- the observer will need to take arcs and compare them to arc maps in the old spectrograph manual (adjusting , or in the table above - they will adjust the angle until they're are happy with the set of arc lines landing on the CCD)
- once the desired angle has been set, click ''Apply Grating Brake'' in the ''Config'' tab
- lock the grating on the ''Config'' tab
- enable the physical brake on the grating (inside the instrument) by tightening the 4 black bolts (do this - tighten the bolts very carefully to avoid disrupting the grating as that would will slightly change the angle and the process may need to be repeated)
- close up the south cover of the instrument