mz wrote:
... the nib alone could be replaced with the same feed and fitted
back into the same unit, while the nib and feed of the Renew
Points were integral to the unit (like modern Pelikans),
requiring the entire unit to be replaced when changing nibs.

Actually, it's quite simple to pop a Pelikan nib out of a modern Pelikan
nib/feed assembly. The nib/feed assembly consists of three pieces: feed,
feed ring, and nib.... that's it. The feed ring is friction fit over
the nib and around the feed, thus holding those two pieces together.
Unscrew the nib/feed assembly and use a knock-out block to separate the
feed ring and feeder thus freeing the nib. --- B