A friend of mine just a 87 4.2 5 speed yj. it was towed to him because there was no clutch pedal pressure and fluid would spill on your foot. so I replaced the clutch master in the fire wall. After bleeding it still won't hold pressure for long and when you start the Wrangler there is a knocking noise coming from the transmission. Almost sounds like when an engine has rod knock but definitely coming from the transmission. Any ideas what it could be? Damaged clutch causing the knocking and internal slave causing the lack of pressure? Thanks ahead of time.