Next i decided to have a go at repairing the rather nasty looking sponge mark in the light blue at the top of the glass. I used my Trident airbrush acrylic paints for this. After a few goes at matching the colour i managed to get it pretty close!

I brushed this colour on rather than spraying with the airbrush since it is an unlit section. It has been locked in with silver/grey paint behind the glass.