Before my laptop crashed, I had FINALLY found the red ball after DAYS of extensive searching! I read the clues in this thread more than once VERY carefully, and out of the blue I suddenly realised I was doing something different than what everyone else was doing. Once I figured that out, I found the red ball in about two seconds. The trick is to read the posts in this thread very, very carefully!
I'm being cryptic on purpose, but if anyone is sincerely frustrated and about to give up on looking for it, you can PM me and I'll give you my tip.