I have to say the first point under #1 on the link MBM is wrong. It is disturbing to see a company selling brakes when they don't understand how they work.
I don't quite understand the nature of the problem you are having. When brakes are "locked out", what does that mean? Also, I don't think you will ever find a factory setup that does not include residual valves so I would make sure that you have them in the system, either in the master or separate.
