Do the brake pads have a taper in them? If they dont, getting some that have a taper could help. Also make sure they are seated correctly. You can also buy some lubricant to put on the back of the brake plate that contacts the piston to eat up some of the vibrations that cause noise, and lubricating the sliding pins wouldnt hurt either.
I would start with a trip to a car wash(yea really). Brake dust build up can cause noise issues. This dust bonds to the metal parts in the brake system. Soapy water can break this bond. Go to a self service car wash and flood the brakes from inside and outside, you should see black running out of the wheels. Continue until clean, then rinse with clear water. No promises, but we fix a lot of brake noise issues this way. If this doesn't take care of it, tear down and inspection are next. All of the above suggestions may help, but let's start with the cheap and easy stuff first.
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