for gusts of wind or sudden wind velocity increases, the backstay adjuster can be used to quickly and efficiently depower the mainsail without letting out the mainsheet. I have found it to be very helpful on numerous occasions while cruising (i dont race my boat, just other people's boats).
I would bet that you could contact south shore yachts in canada (South Shore Yachts | Certified Yacht Broker | C&C Parts and Service
) to get the specs on a replacement plate/block/etc. Or, contact the cnc photo album site (C&C Yachts - C&C Photo Album & Resource Center
) and look there.