240zadmire

Hello, I replaced the master cylinder because it leaked at where the booster strike the cylinder. What I have done: - bleed/flush the old fluid 3 times starting rear driver --> rear passenger --> front passenger --> front driver. Pressing on the brake pedal, I feel constant pressure from start to all the way depleted. I had my son press as hard as he can (10 years old). The brake seem to hold the tire, but if I try to turn the tires, I can still turn it. It is not supper hard to turn the tire. BTW, I'm 140lbs, average build and I don't think I'm that strong. what I notice is that if I block the brake check valve going to the manifold, then it is really hard to press the brake. I mean, you cannot press it at all. I searched online to check the booster functioning using my month to blow/suck and seem to be ok. I also check the brake check valve and seem to be ok too. What am I missing/doing wrong here. Please help. regards,