@ALB, thanks. I'll check out Gene Berg. This engine was freshly rebuilt in 2003 but sat unturned until I bought it a year and a half ago. It was in a garage but the door was mostly open and just a few hundred yards from the North Shore surf. I suspect the ubiquitous salt air corroded the little twisted ends that attach the blades. I'll know more when I get things apart. Thanks again for the tip.