So.. a relatively simple repaint.

Check airbrush - can't maintain pressure. Since it's been subject to 43C temperatures recently, disassemble compressor, clean, reassemble, re-calibrate, all is well.

OK, base coat brush watered down Jo Sonja olive green as a stain. Wait a day to cure.
Airbrush another thin coat, this time Jo Sonja olive green mixed with Jo Sonja flow medium.
Another coat of the same, more flow medium to give full opacity and a smooth satin finish.
Thoroughly clean airbrush with water, 3 full hoppers through it.
Wait overnight.

See that the flow medium has acted as an excellent acrylic paint stripper and glue dissolver. Wings both off, tail fins off.
Use hot water, dishwashing liquid, and old toothbrush to clean up the parts.
Oh well, didn't need the existing decals anyway. Softened by the flow medium they've just come off too.
Note to self - don't use Jo Sonja flow medium except on shapeways, never on Ares models.
Drop part of tail. Spend 45 mins searching on floor for it. Find it on table.

Test airbrush. No paint flow.
Disassemble airbrush, cleaning needle, then using interdental brushes to get out the glunge from the flow medium.
Drop needle retaining screw on table. Spend 45 mins searching for it, find it on floor.
Paint not flowing - spend 20 minutes adjusting needle and reassembling airbrush.
Test passed.

Reassemble model, using CA glue.

Design decals.
Print test. Bleah.
Print printer test pattern - no yellow.
Perform head clean procedure. Test. Then again. Test. No change.
Replace yellow cartridge. Print test pattern. Black now spotty.
Replace black cartridge.
Cyan cartridge not recognised, replace cyan cartridge.
Print test pattern. It works!

Mix 7:2 yellow:black Aldi airbrush colour.
Brush on as a stain, slightly diluted with water.
Wait an hour.
Airbush with same mix without dilution.
Wait an hour.
Repeat.
Wait an hour.
Use fine brush to touch up areas not safe to airbrush, round transparencies.
Notice olive thumbprint on grey bottom surface from when touching up.
Count to 10.
Repaint entire bottom surface light grey. Only one coat needed. Took a minute.

Print test decals - printer not responding, no wifi connection.
Reset printer. No joy.
Reset computer. No joy.
Reset router. No joy.
Search through process list, remove fax/printer service.
Print test decals - great.
Print on decal paper.

Spray decals with White Knight Satin.

While waiting to dry, compose this post.

Actual time spent repainting successfully - 30 mins. Plus much wait time.

Still to come:
Cut out and apply decals.
Wait a day.
Mask transparencies with Play Dough, and spray satin coat.