Is there a trick to bleeding Eldo calipers?

I just replaced the front right disk brake caliper on a 74 eldorado. The problem is that I can't get it to squirt flid out when I bleed it (with another person helping). Just a dribble. After trying, the other brakes work but the new piston won't move. Any trick to bleeding these eldo brakes? The manual refers to using a special tool on the combination valve. I am not familiar with this item. Thnaks, Larry

Its possible you might have a proportioning valve out, causing the original problem that made you replace that caliper....