Quoted from hoov:
Dirt - thanks for the tip.
So you're saying I can apply goop and scrub away with a soft cotton rag and not worry at all about paint loss? If so, great. That's what I'm looking for.
No. Any mechanical action (like scrubbing with anything) will always have the potential to remove whatever is being rubbed. That would be true of even a dry soft cotton rag (especially on the plastic decagon score reels - those are the most sensitive). Fabric is too abrasive to use (even cotton).
I use an old soft toothbrush and just my fingers to spread and work the Goop around, letting it sit and do the work more than scrubbing. The toothbrush is mostly to get in the crevices and corners, and work the Goop off while rinsing.
That's for those plastic score reels. Credit wheels, the older metal score reels, and the apron, where the ink is baked on more, I still use Goop, but will also use a damp Magic Eraser to remove scuff marks and such (damp only with water, no chemicals).
Any ink can be removed if one is vigorous and persistent enough. The goal is to remove the layer of grime, and leave the ink alone, so there's still a balance. But my own experience is that one doesn't have to be nearly as careful using Goop (without using another abrasive, like a cloth).
Always best to try it on spare parts first, to get a feel for it and see how far you can push it though.