My '86 420SEL has dragging front brakes that make a high pitched squeal over 30mph. It started really soft, but the last few weeks it has gotten downright annoying when the windows are down. I have checked the brakes and everything looks okay, and the brakes work really wonderfully, although when jacked up the front wheels do not spin freely. I don't know what the problem is. Also, if I put my foot on the brake pedal the slightest bit, the sound stops instantly. Once released it is back in two seconds. Any help would be appreciated greatly, as I am somewhat embarrassed to make these sounds while driving around.