Michel
I found the float guide pins bent on mine as well. I'm told that this is caused by over tightening the float chamber bolt on the bottom. Mine were so bad the floats stuck in the top position so I just bent them back and it's been fine. I wouldn't bother buying new chambers if I were you.
What type of seal do you have around the float chamber bolt? Is it an O ring or a flat washer? If it's the flat washer, Rotax don't sell them any more and you have to upgrade to the new design which isn't cheap. I have a good 1 dollar solution if you're interested,I fitted it to mine and it works just great.
Mike