I think you would be better off skipping the New Cyanotype chemistry and go back to the basic stuff. Not to throw shade on Mike Weir, but we aren't chemists like him. I've always thought the New Cyanotype process was overly complicated chemically and has too many issues if you stray from perfect, but you already have found that out. Besides, a lot has changed since he came up with that process. I don't think you need it at all anymore to produce beautiful cyanotypes. Maybe back in the 90s, but now you can use the standard chemistry and get fantastic results, and it is much more simple that way. Occam's razor for the win.