Another stupid question:how to remove this screw:
I would put penetrating oil right at the base of the tip that projects up in the pic for several days and lock a good vise grip on the tipabovr the threads. Is there room to get a socket on the bolt head or there no flats on it? Is there any kind of recess in the bolt head. I have a small wire brush in a Dremel tool, I would remove the rust from the projecting threads first.
Got it out. Everyone struggling, just take the hardest grip of your life from that rubber part, there is a little metal ring under it, and start unscrewing.