When stopped on a slight incline, transmission in neutral, the clutch will not disengage, and the transmission cannot be put into any gear. Pedal feel is nil. Driving uphill the clutch works fine, shifting well, this only occurs at stop signs or traffic lights, facing uphill. When level, or facing downhill, the problem doesn't occur. I've bled the system repeatedly, changed out master and slave cylinders, plus the flex line. I've added an adjustable pushrod to the slave cylinder, and the problem persists. Any ideas?