Windsor Rapid Wiring

There should be some fuses under the seat on drivers side under mains power box. Have you checked the globe, and if so check earth at the side light location.

Shane.

The usual reason markers dont work is bad earths and a good clean and a new bulb fixes it.
Also give the connectors a rub with fine sandpaper as they corrode and give a bad connection to the bulb.

All the wires run through the walls so you wont be able to get at them without considerable trouble and expense.

Frequently some idiot has put the cover on upside down and it has filled with water. Drain holes are best at the bottom.

You will probably find it's the earth, take the cover off the light and remove and re fit the light mounting screws. On my Rapid those screws got rusty and would not make a good earth. I also made a jumper wire from one of those screws to the earth on the globe. No problems since.

Cheers.