I'm currently working on my Shimano Sora rear brake. I finished the front one yesterday, but now I can't seem to get it set up properly because it's either binding or there's play. It seems to me that the setting on the centre pull arm when it is mounted on to the frame compared to when it is off. I have the locknut tight enough and the setscrew in, but this doesn't seem to help. Does any one else have problems making this adjustment? I've always found it one of the toughest bike repairs to do.