Mine were turned a half quarter turns and there was an improvement (a little). It stays on wide zoom but when the lens is shaken when walking, it creeps half way. I do not want to go further, I am afraid of damaging some internal parts on it. Guess I still have to do the safest way... lensbands.
EdIT: Out of the topic. I already took off the front elements glass of my 24 105 for cleaning before. Will clean it again and try to figure out if there is another way to tighten it up. I'm confident on removing the front glass but when it comes to little screws (especially if I do not the reasons fo them being there), I tend to back off very often. Cheers.