Very carefully! I always avoid touching the black ink at all. It comes right off, especially if wetted. I would use a-tips dabbed in water first to see if that will remove whatever goo is on that reel. If water doesn’t work, graduate to isopropyl alcohol. Again, don’t let it touch the black at all! Good luck.

GoJo NON pumice hand cleaner. Never lost a reel yet and have done 100’s. Tip given to me by Steve Young many many moons ago.
ALWAYS TEST A LITTLE SPOT FIRST NO MATTER WHAT RECOMMENDED!

I test on the 1 or 7 digit because they are the easiest to fix if you remove the ink

#2 for Gojo and Steve Young’s tip. I’ve been cleaning them that way since Steve passed on the tip - about 40 years ago.

I just use warm water little to no soap

This stuff? Thanks for the tip!

A164CC99-158F-4A55-B42A-33963F4CAED9 (resized).jpeg

Yes. TEST SMALL AREA FIRST as I mentioned. I never had a problem but always that chance.
Apply, gently rub around, wipe dry with paper towel. You can also use a soft bristle toothbrush(CAREFULLY !) if needed.

If you want to go the route of using stick on numbers, just go with a heavy duty cleaner for your existing reels. Something like Castro Super Clean or Mean Green. They should clean the reels, but will most likely take the ink too. We thought you were trying to save the ink.

I have a reproduction file for the reel numbers on my website http://www.inkochnito.nl

http://www.pinballrebel.com/pinball/cards/Gottlieb/Gottlieb_Score_Reel_Numbers_1-10.zip
This is not the correct font, but can you see if the strip fits?
Are the numbers at the correct place?
Maybe I can change the font to match yours.
It would be helpfull to have some more images of the numbers.

PM send....

It looks like the very first image in this tread show a reel with 0 to 10 if I'm not mistaken.

Will Gojo take the yellowing off the plastic to make it white again?

No. So many posts about yellowing plastics as methods tried, different products, and really not great results. My belief is you can’t get it out. Make it a little better,(?) maybe. Same with vintage drums for White Marine Pearl wrap. Just can’t bring it back, but once again maybe better.

Yellowing and reversal depends on far too many factors and incidentals. Such as type of plastic, how old is it, and what was it exposed to (because natural outgassing mixed with exposure to UV, heat, nicotine, and other reagents, let alone independently and/or mixed in different ratios, does NOT provide the same end result).

So while there are various "retrobrite" recipes out there with varying degrees of situational effectiveness, they are not one-size-fits-all. Sometimes it seems effective... or the best you might be able to get is "better" but still not restored OEM. And it could even make things worse (make the plastic more brittle) or be subject to re-yellowing over time - sometimes very quickly.

Truly not worth the hassle and risk if replacement parts exist, IMO. Of course they don't always, so it's still an option when you're desperate. As a very last resort.