Originally Posted by ironyusa
The best way to get it tight is to loosen the 2 grub screws and tighten the lower air transfer tube (wiggle it gently while tightening). Then retighten the grub screws. You can put an extremely set of screws in the opposite side of the frame if you'd like extra assurance. Remember the air transfer tube is what does most of the holding, so don't over tighten the screws.
Yep what irony said. The lower air transfer tube is what keeps the ASA tight. The screws are secondary so cranking the screws down more and more will not help and will eventually damage them.