Rob’s guide to servicing the GTO’s rear aero.
Needed:
Carpet, towels, 10 mm socket and driver, pliers, cross-point screwdriver, small screwdriver for prodding, special tool (or strong finger nails) for lifting plastic trim.
Open the boot, use the pliers to remove the rubber covers on the four bolts.
Remove the 10 mm nuts.
Remove the two
screws holding the clips for the boot cover. 
Lever the plastic trim off its many edge catches and two more central ones.
I found this special tool under the carpet after a visit to the Mitsi garage. Have a look, you never know!
Flex the middle part of the trim towards you then ease it around the gas strut joint at each side of the boot lid.
Use whatever strange tool you can find to squeeze from
front and back (not sides) the piece of the plastic clip holding the wiring
connector to the boot lid.
Then squeeze the little clip to separate the connector.
Use finger tip or screwdriver
to push the rubber grommet up through the lid.
Remove the last three 10 mm nuts.
Close the boot!
Lift off the wing and lay upside-down on a fairly large piece of carpet.
Carefully ease off the rubber sheet. If it tears, tape it up now.
Remove this screw and the same one on the other bracket.
Do NOT remove any of the other 4 screws, otherwise you may be tempted to lift
the whole assembly.
If you do, it will swivel, putting strain on the supporting bushes which are glued to the wing (see right!).
Then you’ll need some super glue.
i.e. do not remove the screw shown left, or the one to its
left or the matching pair on the right.
Separate the connector for the top level stop light.
Carefully peel up the two end rubber seals (again, repair
any damage) and remove the two bolts in each.
The two parts of the wing can now be separated.
The sliding mechanism at each end can now be lightly greased.
Three screws hold the motor assembly in place. Remove
and invert.
Breathe a sigh of relief if you can see gears with all teeth present and traces of grease.
Breathe an even bigger sigh if the same applies to the two threaded rods that are moved by these gears to activate the aero.
If the news is bad, and you want a working aero, prepare for a big bill now.
Microswitches can be checked and replaced at this stage. If you do this, do NOT cut the wires. De-solder them, remove as much solder as possible and use emery paper so the ends will go into the holes in the connectors on the new switches. The existing wires are barely long enough for their purpose.
All the above took me just over an hour.
Re-assembly:
This is clearly a reverse of the above.
If the motor has been removed, make sure both of the screwed flexible rods are fully extended into the lifting mechanisms (aero closed). Make sure the pins in the white plastic sliders are pushed fully into the holes in the ends of the screwed flexible rods.
When mating up the two halves of the aero, the plastic pieces shown being removed in this photo need to slot onto those pins. If they do not slot in, remove, adjust and try again – do NOT screw them down; you’ll only have to take it apart when you discover the aero doesn’t move at that end.
The rubber sleeves can be a bit of a pain to get back in place.
If you removed the rubber seals, replace them now.
Testing:
After lubricating, repairing or inspection it is possible to test the functioning of separate components without total re-assembly. This is worth doing as assembly can be a problem and it’s best to find out there’s a problem before you’ve spent another hour and a half fitting the aero back on the boot.
This is how I did it:
Lash the boot lid down low enough so the power can be connected.
Pad the wings before putting the aero across them for testing.
All being well the aero can now be attached to the boot lid.
Don’t forget to replace the large rubber seal before you go any further!
Close the boot and pad it with towels to prevent the bolts scratching the paintwork while you wriggle the rubber grommet back into its holes.
Replace all the boot lid nuts, reconnect the power, test again then replace the plastic trim.