I have used two methods. 1 fill the resivoir and leave it for around half an hour. Then keep pumping the peddle all the way down and all the way up quickly. After twenty odd pumps stop for around a minute. Repeat the process three to four times. If the method is working you should start to feel a little bit of pressure towards the bottom. If so keep repeating the pedal pumping method until you have a good pedal feel. If this doesn't work. Method 2, find an old plastic bottle (small coke bottle is a good start) make sure is clean and dry inside. Find a piece of vacuum hose or similar plastic hose that will go over the bleeding nipple at the concentric bearing. Make sure it's a nice fit. Drill a hole in the screw on bottle cap so you can put the hose into the bottle. Again make sure the hole in the cap is a snug fit for the hose. Half fill the bottle with clean brake fluid. Open the bleeding nipple turn the bottle with fluid upside down and put the hose on the nipple. Lightly squeeze the bottle this will force the fluid in and push all the air and eventually fluid into the master cylinder. Its generally best having the resivoir empty first. Get someone to keep an eye on the resivoir fluid so it doesn't overflow. I find this is the best way to bleed the system if conventional methods. Once the fluid level has reached the maximum mark close the nipple while still squeezing the bottle. Remove the hose and check the pedal operation. If you can't get the fluid to rise in the resivoir you pedal rod will be riding and you need to check things.