Andy - re: HY/RD brakes, two PDFs and a video on their web site.
Install video:
http://www.youtube.com/v/_8T6cON6y_Y&rel=1Technical Bulletin: (basically the check I did last night)
http://www.trpbrakes.com/userfiles/file/TRP%20HYRD%20Technical%20Bulletin%20English%20Rev%20B.pdfInstall and Adjustment manual: (Section B refers to how to adjust the cable).
https://www.trpbrakes.com/userfiles/file/HYRD_Final.pdfSo essentially what I would do would be to undo the cable grip bolt. Fully turn the barrel adjustment into the calliper (clockwise as you look down the cable to the brake).
Then screw in the lock knob, pull the cable inner hard and tighten the cable grip bolt.
If (with the lock knob still screwed in) there is still movement in the leaver, you can use the barrel adjuster to take up any remaining slack, 2 things to note though,
- there is only 1.5 turns of adjustment, so if you have gone more than say half a turn, you probably didn't pull the cable tight enough.
- once you have adjusted the barrel to tighten the cable outer, it might be hard to undo the lock knob, so back off the barrel slightly then undo the lock knob and adjust the barrel back to where it was.
I think the problem on yours is the above process wasn't followed so the actuator arm (the bit the cable is attached to) isn't returning to the right place when the brake is off, so the vent that allows the pad wear compensation happening - more detail in the above technical bulletin.