Have mushy brakes. Tried to bleed brakes. The bleed screw took lots of work to get loose. Rusted. Finally got it loose, and it came out. Would not go back in. Took to Advanced Auto and said it was bad, sold me new one. It went in fine, but would not tighten. Talked to Advanced Auto associate, he said it requires only hand tightening. Tried that, but it still leaks out fluid when brake is depressed. What do I do?