Be careful of eucalyptus oil, it has many properties and MAY affect the paint.
Id be using a cotton bud tip with a small amount on it and test in a non conspicuous place on the pf. You will need to remove the oil also after use - can use meths for this on a soft rag - itll take out the oils, then wax straight after.
problem with mould is that it stains and the customer may have to live with this if it doesnt come off. The spores can go deep into the pf and the action of getting them out will start to affect the paint.
Do NOT use magic eraser on these old PF's. It WILL start to rub the paint away.
Meths wont harm it or isopropyl, but if in doubt test first. ( has never harmed any of mine)
I havent come across this problem with any of my games, but a method i have used to good effect to remove stubborn dirt is to use meths on a soft cloth and gently rub at it in a circular motion, this will loosen the grime but may not lift it. Then get a make up pad with a lint front, soak in meths ( no too wet so its dripping) and place flat over the area. The osmotic effect of the pad drying and the dirt dissolving action of the meths will lift some if not all the dirt to the surface and into the pad.
So leave the pad to dry and then take off. This may or may not work - depends how deep the problem is.
You MUST wax straight afterwards though - alcohol will remove the natural oils in the timber also and these need to be replaced.
Good luck, and remember - test first with anything you use on these PF's
