Fell down a rabbit hole. Now cleaning some NES carts, discovered my nes Shingen has some nasty brown oil discoloration. Fingers crossed for baking soda.

Baking soda appears to have no effect after an hour of exposure. Scrapping the experiment and moving on to white vinegar. Will check results in two hours.

It's been an hour and I'm not sure I see any improvement from the vinegar. But I'll leave the cart soaking overnight. It's angled so that the contracts are dry and the stain is fully submerged. Tomorrow we'll try something else.

I can't tell but I think the stain may have lightened a smidge after a night bath in white vinegar. Still a failure though. Also took some whightening toothpaste to it at one point, didn't expect any results from that and was not disappointed.

I've now wrapped the top half of the cart (with label) in a hand towel, rubbed the stain down in lemon juice and set it to sit in the sunlight. Will report back this afternoon.

Aborting experiments. Repeat. Aborting experiments. The brown stain remains faintly vigilant, but the lemon and vinegar have reacted to leave a light "bleach" line on the plastic.

Final cart. Sorry there was no before image.