AT LAST! Thanks to several members of my beloved QuiltArt group, I finally have an answer to why some of the posted images to my blog haven't been able to be enlarged. Evidently the filenames of the images had spaces in them, which Blogger sometimes doesn't recognize. The solution is to use underlines instead of spaces.
I've gone back and reposted the latest few images ... particularly the April 8 "A Beaded Postcard", which is much clearer in the enlarged (and the super-enlarged) versions.
What a relief to finally get this figured out (no thanks to Blogger, by the way ... as usual, I had to rely on "a little help from my friends" ... which is more fun anyway.)