All points taken into account, guys. No more glasfiber pens. Yesterday I tested a switch with the pencil eraser combined with de-oxit 100 and I must say I'm pretty impressed with the results. I was planning on only cleaning and preserving the slider parts, but it looks like the old brown grease of the mechanical parts has found it’s way into the slider parts. So I cleaned the entire switch and I will regrease the mechanical parts with ceramic grease.