Williams added a 'fix', I have the notes in my manual but a copy can be found here

http://mirror2.ipdb.org/files/1308/Williams_1988_Jokerz_William_Service_Tip_For_Audio_Hum.pdf

I've heard it doesn't fix it for everyone. I haven't tried it on mine yet, but its coming soon. I've heard of others adding resistors to the speaker lines as well.

https://www.michaels.com/golden-fluid-acrylics-1oz/M10043281.html looks to be a close match, Cerulean Blue Chromium may need to add some black to darken or white to ligthen it up a bit depending on the tone/fade of yours.

I haven't tried it but was looking this over for my own and felt it was close. You have to be careful because its a 'warm' blue vs a 'cold blue' if you choose the wrong one it will look horrible even if its a tonal match.

Remember too that most paint dries down a bit darker. so paint some on a piece of cardboard to see how it dries down, and if you have a mix a batch mix up extra and save it in a jar for repairs later down the road.

I have no idea what they were thinking with this color scheme. It sure does stand out, but in a weird papa smurf meets bad santa. Its has great art, but wonder if it would have done better with some change to the color scheme.

Golden Acrylic's are expensive and usually in the painting isle of Michaels or Hobby Lobby. You'll also find acrylic paint in the hobby area, its usually much cheaper.

I'd start with the golden grab it, and take it to the cheap hobby isle and compare colors. Again the key is color temperature. Some people won't get that but it really shows in blues in this value range. There's a Jokers for sale in the adds with some patch touchup's (in Florida) and that's clearly what happens. It was touched up with a close value but a cool temperature blue and it shows. Most warms are titled or have Cerulian in the name but not always. If your not sure cooler blues usually look darker. Warms are like the sky, cools may seem a bit 'bluer' to most people. plain label BLUE will almost alway be a mix of both.

Anyway here's what you get when you buy golden, best pigments and base, so its longer lasting, less prone to fade, and a base that will level flatter and is more flexible in how thick or thin it is while remaining flat. Its meant for fine art painting on canvas and board.

The cheaper stuff can work, and the price is usually a buck or two a bottle vs 10 bucks or so for Golden Brand. Its suited for crafting and can still work. I noticed when I visited TNT pinball (on YouTube) they used the craft paints and it seemed to work for them, so no need to shy away from them.

Also recommend if you buy a white / black / and blue to mix values, get the same brand. The bases and pigments are more certain to blend, especially important when looking at the cheap paints.

it shouldn't take more than a few drops of black or white to shift it, so drop, mix, test.

Probably more color theory than you wanted but hoping it helps avoid a poor result. Ultimately a little time to test and mix to get the right match will save you the trouble of trying to repaint all of the color to match.

Good luck!