Well, it's done. All the recorded shows I lost when the Expander died are available on Hulu Plus or otherwise, so I decided the simplest was to just divorce the failed expander and put the new one on in it's place. The Tivo performed MULTIPLE restarts after removing the expander. I thought it was stuck in a loop...."Starting Up...." then black screen, the "Just a few minutes more..." then black screen, then "Starting Up..." over and over and over. I had my iPad in my lap during this process and I was reading other threads here at the forum and I learned I should just be patient and let Tivo do it's magic. Sure enough, much to my relief, it finally ended it's rebooting tasks and played the little welcome cartoon. Hooray!
After the successful bootup, there was only ONE recording left in My Shows that would still play...and that happened to be a recording that I'd made before I added the original extender. (Makes sense, huh?) Probably about 50% of the original recordings were now gone from My Shows, and all the rest that were listed there failed to play with a message saying that the Tivo must've tried to record from a channel that had no signal or something like that. I wonder why all the bad recordings didn't just disappear after the divorce? Oh well...I methodically deleted everything (except for that one show previously mentioned) and made some test recordings. Everything seemed fine, and a couple of downloaded podcasts (Tekzilla, CNet) showed up and they worked OK, so I dod a reboot just for drill, and then added the new expander drive.
Now I'm back to 400-some hours of capacity with only 1% used.
Divorcing the old drive took 2-3 hours (!!) and all told getting everything going again took about 4-5 hours. Glad I didn't have to start from scratch with a guided setup. My Season Passes are still there, so I'll pick up from here and continue on.
I should probably consider an internal hard drive upgrade and skip the expander idea, but once an internal drive fails that seems like it'd be a MUCH more time consuming process than this was, and this certainly wasn't quick! I used to have a fully tricked-out Series 1 with huge capacity and an Ethernet board and I also added a 2nd internal drive to my Humax Series 2 so I'm no stranger to imaging drives and poking around inside a Tivo. But I gotta say Tivo's expander idea was certainly a lot less hassle than the internal upgrades. Just wish Tivo had included some time estimates with their instructions to reassure me that everything was going as planned and not to panic after a dozen or so reboots!
This gave me a chance to fully explore Hulu Plus. I'm blown away with how well the app worked and OMG, the picture quality was (to my eye) just as good as if I were watching one of my OTA HD recordings from my antenna! I'm thinking the monthly cost for Hulu Plus is a pretty darn good deal considering what you get for that $7.99.
Thanks everyone for all your assistance. I'd have loved to have had the time to poke around in the failed hard drive and see if I could save any of the shows, but having just moved to a new house I've got 2 years worth of honey-dos on my list that take priority.