I installed a MotoWheels slave the end of last year and it took a lot to get it to bleed. I started by filling the slave with fluid with an eyedropper. Then used a Mighty Vac to get the flow going. Then used a rapid pumping action on the clutch lever (with cap installed of course). If you pump the lever slowly you may not get it to bleed at all. For some reason, rapid pumping of the lever helps draw fluid from the resevior, push the fluid through the line and force the air to where the bleed nipple is. Give it a try, it worked well for me.