Had to replace the slave clutch on a 2005 MK4 Jetta because I accidentally tore the boot. I can't get the air out of the clutch. I am bleeding with a hose attached to the nipple and I am opening it when the clutch is fully depressed and closing it before the pedal is released. There are microfine bubbles in the stream that won't bleed out. I've been through three pints of brake fluid. It seems like there is an air leak somewhere in the system (but I had no problems with the system before). I think I might be hearing a hissing sound near the fluid reservoir when the pedal is depressed. Any ideas?