I have internal halyards on my Ballad mast. The running rigging had the original wire/rope style halyards. When I took the masthead off the mast and looked inside I could see the wire halyards had cut half way through the bolt that holds the main shroud attachment tangs. I'll replace the bolt and switch to all-rope halyards and this should fix the problem. If you have a similar setup it might be worth checking next time the mast is down.
Peter
#1085 'Bennath'