re: 1992 400E.

What can cause brakes to pulsate? Besides warped rotors. The pulsating was quite pronounced so I put on new new Balo rotors and new pads, it was fine for a couple of months, but now it has come back and is getting worse. It's more noticeable when the brakes warm up, not so much when cold. I'm assuming there must be something wrong with a caliper - but what? The calipers must not fail often because dealers don't stock them - although they do have a caliper rebuild kit for about $60. But what could cause the pulsating to come back so soon?