Best to think of this logically. DOT 4 as a fluid is heavier than air, so will want to flow to the lowest point in the system. Gravity and all that. Air will then want to rise through the fluid to the top.I fit the original banjo bolt but struggled to get clutch fluid to flow. I may not have been using the Mityvac correctly so its back to the garage to sort it out. If I can't do this job, I'm doomed.....
Fill the reservoir, and crack open the banjo bolt or bleeder at the clutch slave. Make sure to wrap some shop rags around it so the fluid doesn't go every where. Soon enough, fluid will start to dribble out. Tighten it back up once it does.
You may have to slightly pull the clutch lever in to align the port on the piston to allow the fluid to move. Once it aligns though, fluid should freely flow to the slave.
You have now gravity bled the system. That does not mean all the air is out, but it does mean you have fluid at the slave cylinder. Just proceed on a normal bleed procedure once you've got fluid down to the slave.
The mighty vac is good for doing a bleed but you gotta get fluid down to the slave first. If there is a bleeder on the slave, hook the suction side of the Might Vac to that, and the outlet side hook up a hose and run it to the reservoir.
Once you do that, crack open the bleeder and pump the might vac. You should get clear fluid, without bubbles in a short time.
Again, you may have to slightly pull the clutch lever in to align the port on the piston to allow the fluid to flow. Make sure to keep the reservoir full while doing this. Hope that helps......sean