Hi Sigma
> Do I have to use after the cleaning some fluid grease?
> (Don't know the correct English word for it sorry)
I use "Caig Fader Lube".
There is a 5% version, which is used for solving and washing out the
dirt, and a 100% version, which is used as "grease", which seals and
also avoids remaining "micro scratchiness" as the fluid is a littlebit
conductive (but with very high resistance). It might be not the cheapest
solution, but I am quite happy with it.
Florian