No need to drain the oil. Put it on kick stand. When you take off clutch cover you'll lose less than an ounce of oil.
You can get the clutch cover off without draining the oil out. Put the front tire on a 2x4 piece of wood. I know because I did it to do the Brocks Clutch mod. Hopefully you can get some fluid down to the slave from the master cylinder first. Good luck.
Did you ever check in the master cylinder where you put in the brake fluid that the return line is not clogged. It's the little small hole that looks like a jet. When you pull the lever it should shoot up a small stream of break fluid. If not it's clogged, and not allowing the brake fluid to flow properly.
result...............still sounds odd that the clutch was slipping just due to the line as to me that would give no clutch rather than slip.
Slipping is only caused by something holding pressure in the hydraulics,wear on the plates or a mechanical fault within the clutch assembly
but heah its working
So where's the pics of a bking wheelie? Really glad you got it figured out
thats great six...i happy for you that you got it worked out