D&R Marine or local store
The Inspection / Bailing ports in the cockpit are available from most marine stores, Beckson is the most popular brand I replaced mine with these. You will be better off replacing the whole thing, rather than just the caps. You may need to slightly enlarge the holes in the fiberglass to fit in the new deckplates, but they will fit. D&R Marine has these as well, and I think Rudy's price is a little better than the chain stores (usual price is less than $10). These new ports are a BIG improvement for many reasons, not the least of which is that they have a coarser thread.As far as a centerboard diagram, Rudy has one that he includes wit hthe rigging guide that he sells. I also have an expanded version of the DS II Manual that I make available for $7.00 including postage. E-mail me for details.I've included a link to D&R Marine if you want to check Rudy's price on the inspection ports.