Can anyone find a photo of the "LEGO bricks, not LEGOS" insert?
Here you go, from a scan of a 1985 catalog at Retroist. (I'm still looking for a version without the Retroist URL smeared across the bottom.)

The text reads, verbatim:

Dear Parents and Children
LEGO® is a brand name that is very special to all of us in the LEGO Group Companies. We would sincerely appreciate your help in keeping it special by referring to our bricks as &quot;LEGO Bricks or Toys&quot; and not just &quot;LEGOS&quot;. By doing so, you will be helping to protect and preserve a brand that stands for quality the world over.
If at any time we can be of service to you regarding our products, please feel free to write to us.
Susan Williams

The text you quote above is slightly different and may be a variant from a different year, or perhaps it's just slightly misremembered.
It's from one of the &quot;mini-catalogs&quot; that came with the sets, so this was both a catalog and a box insert.