If you tried toeing them in and it didn't help try a little toe OUT. That's right, the leading edge touches first. It sounds odd and isn't in any books or online pages but I've used toe out a couple of times now and it fixed the squeal where nothing else did.

Squeal is not about the quality or price of the arms and pivots. It IS about how the system resonates. Kill the sympathetic vibrations and the squeal or shudder goes away. You may well pay big bucks for a set of Paul's or something else based on recomendations from folks here only to find that they STILL squeal like a stuck pig on YOUR bike.

In one case I'm riding now I've got the low profile MTB style Kookstop salmon's on the bike because it's the only thing that gives me the clearance I need to be able to retract the arms enough to remove the wheels. NOTHING would stop them from singing like a soprano in heat until I cut away the first leading (as in rearwards) block of the pad. With the shorter effective pad the squeal went away. I altered the system that was producing the resonance far enough out that it doesn't sing any longer. But put those same arms and pads onto a different frame and fork or even change to a differnet wheelset that uses a different extrusion alloy in the rim and it's quite possible that the problem would be back again.