I have this Spin Out I'm cleaning up. The cab is really yellow - I think it's been varnished with some oil based product back in the day, but it may just be cigarette smoke. Not too sure. There's some touchups so somebody at some point did some restoration on it and it would make sense that they'd varnished it afterwards.
Anyway I wasn't planning on doing this but just tried some Goof Off and Magic Eraser on the top of the head.
This is what it looks like. The point between the yellow being gone and removing the speckles is pretty narrow so I think I may try to do the whole cab and then go back and redo the speckles. It looks like there's the risk of getting some white off too but so far it's not too bad.
Also the head is the yellowest part of the machine.
Here's what it looks like.