As good as Da Book is -- and I do consider it indispensable for anybody who wants to work on pens -- it is not free of error. Some of the things Frank recommends are not good ideas -- such as the use of nail polish for securing sacs. Nail polish damages celluloid irreparably, and this is
not something you can just dismiss because there are a surprising number of 1940s pens with sections made of celluloid (including Waterman Commando and Taperite, and some Skylines).
So, as with any reference material, use Da Book with care.

I remember once Frank and I were talking about repair work, and he noticed the ink on my hands. I said it was inevitable, and he said, "If you're getting ink on your hands, you're doing it wrong." Which is generally true unless you're adjusting nibs in real time.