7. Never annoy the fuze in this manner.
Not really. The actual instruction is “7. Hold arming vane by hub, press it into position.” This illustration is from the WWII US Army Air Force Bombardier’s Information File Armament section, said manual in PDF form at the link.
On the same page, though I think oddly not highlighted in any way, is this sensible advice: “Don’t bump detonator against side of cavity.” I’d’ve probably put it this way: