It's obviously a magnetism issue. Even teflon screws will illustrate that. The ferrous type screws cause a subtle but quite audible perturbation in the magnetic field lines of the speaker magnet. Another option would be to demag the screws periodically. Be sure to demag all those tiny ferrous screws on the component chassis while you're at it.
Brass screws make a real difference on Dunlavy s ?
As some of you know, I have just about every model speaker John Dunlavy ever designed. I've tried a few tweaks, but never replacing the standard driver attachment screws with brass ones. I've read some posts that it really does make a difference, but before I make a run to the hardware store, I would appreciate any thoughts on the matter. Thanks in advance!