The truck is a 1990 F-350 4x4, internal slave cylinder,zf tranny. When I bought it the tranny was out because the clutch was wasted. I put a new clutch disc, through out bearing and pressure plate in and installed the tranny. When I filled up the master cylinder and tried bleeding the system nothing came out the bleed screw. i took the line off at the master cylinder only a little bit dribbled out. When I depress the clutch pedal nothing happens and the master cylinder doesn't empty. I suspect I need a new master cylinder or am I totally missing something?