The WSS cannot be cleaned or anything. It either works or doesn't. I could imagine dirt getting in there, but with the tolerance between the WSS and the rings it'* unlikely. The WSS frequently go bad, and yes you need a whole new hub to get a new sensor. I worked for days trying to extract the old sensor in a spare hub, trust me, it'* not going to happen. If you really want your ABS, go to the jyard and get a new hub and put it in. It'll either work or it won't, if it doesn't work, hopefully your yard will replace it [mine does]. Otherwise you will be spending an arm and a leg + the cost of a new car to fix a primitive ABS system. I have ABS in my foot and I can what I would call shiver my leg for ABS. Works fine for me... but i'm a frugal little ****.

I am afraid as you said to lose an arm and a leg in this repair.
Is unplugging the ABS fuse is feasible and live witout this "primitive ABS" system
with no site effect other than jsut losing the ABS pulses function?

Thats just what I did on mine and they went back to regular brakes. Guess next time I have to pull the shaft I'll fix it right.
I do have an abs foot on wet or slippery pavement training myself to lightly pump the pedal with just enough pressure so they don't lock up. Thats how I make it work and if you don't do this in an emergency and expect the abs to kick in you should not pull the fuse. Fix it right and be safe.