I have the same brakes and they really work well. I suspect that a small amount of air generated with a gentle blow into the line is not enough to make it work like it should. Have you tried it with 100lb-ish pressure with the wheel on? When i do that after spinning the wheel it stops and is hard to move.
PS- I found that with the door covers on the mains that the gear was pulling out in flight- I pulled the gear doors off and it works great.