My 1965 BB17 has sliding gooseneck fitting. When I went to the yard last week to step the mast and connect the boom, I got a bit of a chock. The crew at the yard had removed the sliding cart from the mast track and managed to lose it. Oops. I have the t-track (20 milimeter) and the all fitting son the boom. Any tips of where I can find a cart for 20 mm track?