I already had removed these screws a few times, but as far as i have seen I have to remove the whole case including fan and cooler if I want to clean the inner of the fan or the bottom position. Futhermore these four srcews only connect cooler case and fan if I remember right.
So, I`ll perhaps have to disassemble the whole cooler if I want to clean the fins from the inside. Anyway, thx for your advises. They` ll probably help me a lot.