Changes

* - set the grating angle to 0 deg in the SpUpNIC control GUI * - set the telescope vertical * - position the ladder on the north side (so that you ascend from the south) * - undo the two quarter-turn fasteners on the grating hatch * - hold the grating handle at all times while undoing the 3 orange knobs that secure the grating * - the bolts are captive so they will unscrew and slide back, but not fall out * - carefully retract the grating, keeping it level as you do so (you may need to wriggle it slightly if it seems tight) * - take the grating that was in the instrument to the grating room on the NW side of the dome and replace it in its box * - back at the telescope, check that the grating is orientated correctly (2 bolts on 1 side, 1 on the other) before attempting to insert it * - keep the grating level as you insert it, applying firm but gentle pressure until it's flush with the edges of the grating holder frame * - keep hold of the handle and apply gentle upward pressure while you tighten the bolts * - if any of the bolts feel stiff or awkward during tightening, gently wiggle the grating a bit (the bolts should turn quite easily) * - continue tightening until all 3 bolts are fully secure (and can turn no further) * - with all 3 bolts screwed in fully, close the hatch and lock the quarter-turn fasteners * - remove the ladder * - go to the Advanced tab on the control GUI and click the grating angle initialise button (in the bank of buttons on the left)