The rivets on the top of the mainsail have broken and i am left with only one or two rivets holding the two metal plates to the luff and top of the sail. What kind of rivets are they and what size. Can i put them on myself and what caused this. Also does anybody have any tips on lowering the mainsail, Knots on the halyard and just tips on getting the ring off of the hook. This has given me alot of trouble.