After a couple of years user found this light would not come on. Checked OK, eventually found yes it is faulty, not before...

A white plastic gearwheel is loose inside the printer, its 3mm black plastic bearing has broken off its chassis part....

Undo the six screws holding the back panel, remove card disc, and two light reflecting discs. LEDs are a circular tape inside metal frame, in two lengths, and solder blob connecting them appeared dry or broken. Repaired by soldering a bit of wire. Moral: don’t order a new power adapter till the luminare itself is checked!

Searched online for a spare duplexer / rear cover for this printer, relieved to say I did not find one. Found that a 6BA bolt will go through the broken bearing spur, so drilled the duplexer frame 2.5mm and put the spur in a horizontal bench drill as a lathe, put a 2mm drill bit through using this also to take it out to 2.3mm, just holding the drill bit in my fingers. Remove bottom gear with one screw, fit spur with bolt from back onto frame, take some spare grease from the printer mech somewhere for the spur, fit middle gear and nut on with some metal glue (prob not needed). Bottom gear back on, works a treat.