FYI, I opened the 500+ Mbyte .sh3d file with the recursive save and replaced the furniture item containing a reference to a texture used in an object (that is, as opposed to textures accessed through the texture picker window) with a corrected item, and re-saved the file -- which suddenly shrank to 253 Mb. [:D]

So, yeah -- I think you've got this one figured out.

Many, many thanks!