Bob..
Re leech lines, it's my understanding that leech lines are there to control any fluttering in the mains'l leech.
The BR20 with the bendy CF top spar (basically a windsurfing mast) used to suffer badly with leech flutter so the leech line could be used to control this to some extent.
I think my BC23 main is very similar to the BRe, I set mine up by raising the main to it's normal sailing position and tensioning the leech line until it was only just taught, then cleating and securing it off. It's important not to over tension them as you'll hook the leech and you'll not be able to flatten the main in a blow.
If your cleats are broken then I suggest you just tension and secure the line off as best you can (stitching them in?).
To be honest, unless you are a determined racer it may not be worth the cost of replacing them.
Keen racers - and you may well be one? Do use them to control sail shape, as this is pretty difficult when the end of the boom is hanging over the side, the line can be rigged secured at the clew end, go up the leech, round a pivot at the head and back down the luff where it is accessible at fore end of the boom..
Hope this is of some help to you..?
Regards
