WHEEW! that sucks, i can fix pretty much anything on a car, but when someone else's mitts has been in there, its extremely difficult to pinpoint and repair problems. ive seen some horrible mickey-mouse hack jobs and they are almost always hard to reverse.

slave cylinders almost never let go of a line when you loosen them. probably went.

-rear brake lines rusted up
-rupture due to stress and poor shape
- owner attempting to hack a new length of line with compression fittings
-owner successfully screws up slave cylinder threads
-owner says "screw it" and tightens the line up as best he can.
- new owner gets car lines continue to leak
- so much fluid is lost and so much air is replaced now brakes don't work.