I bought a very early H16 that had the same problem. I took the crossbar to a local machine shop and for $20 the guy drilled and tapped the hole in the mast step out to 3/4" and made me a new stainless steel dolphin striker out of 3/4" smooth rod that he threaded on one end and drilled on the other to match the old 9/16" dolphin striker. I think I got a god deal! The other alternative is to get a new mast step, but I bet that's more than twenty bucks!