There's a photo here showing IBM caps where the dyesub has sort of leaked or spread viewtopic.php?p=447136#p447136Waxwood wrote: ↑26 Nov 2019, 20:22I tried the denture tablets last night.
The greenish-yellow tinge on the keycaps has not faded at all. I'm guessing its from smoking and typing on the keyboard.
I'll try to post a photo of these oddly discoloured keycaps and the blurriness of the printing on many of them.
I noticed this problem on several of the keyboards I'm rebuilding.
Do they need retrobrighting? Would that take care of the discoloration?
If that's what yours look like, I don't think any cleaning will help, although if you aren't afraid of using a mild abrasive you could try a "magic eraser" melamine cleaning pad.
If you post a photo you might get better advice from others.