hello Paul

Yes i am using the same master cylinder, I have managed to nail the problem down to the master cylinder when the brakes are stuck on you can crack the pipe that connects to the master cylinder and the pressure is released. I removed the master cylinder about 2 hours ago. and gave it a good clean blowing out all the holes with my airline. I then refitted and bled the entire system so far the brakes are not sticking. Fingers Crossed.