Yes, as you say. I often say that fixing a time machine/time capsule is like doing a rain dance to cure appendicitis. Even pondini (who's info is great!) says this in a few places. Basically, sometimes it just doesn't fix.
Anyway, after copying everything successfully to an external usb disk (and satisfying myself that the historical backups were still accessible using option>browse other backups, I wiped the whole internal drive on the time capsule and wiped the preference files for time machine on my wife's computer and on mine.
Started all new backups from today.
It felt great.
Should've done it a long time ago.
Have a great thanksgiving and thanks again for your help.
Hope this helps someone. I got a new MBP and cloned the drive of my old machine instead of using Migration Assistant during the initial setup. This caused me to lose the connection to my Time Capsule, getting the "already in use (error 35)" message.
As others, I referenced the Pondini website and found the terminal command to reattach the Time Capsule sparseimage.
When I attempted this, I got an error ("failed to attach"). The problem was that on Pondini's page, he shows you dragging the Backups.backupdb directory into Terminal.
Here's the deal. Be careful which Backups.backupdb directory you drag into terminal. It must be the one with your <myMac.sparesebundle> image inside. When I looked for the Backups.backupdb directory in Finder, the one I found turned out to be empty. It was only by connecting to the TC disk (disconnecting in Time Machine prefs and then reconnecting) that a disk image icon called "Time Machine Backups" appeared on the desktop.
Opening this, I found the correct Backups.backupdb directory and dragged it into the Terminal window after typing in the following command:
sudo tmutil inheritbackup
Then it looked like this:
sudo tmutil inheritbackup /Volumes/Time\Machine\ Bacups/Backups.backupdb/myMac.private\ ( \4\)
Ran this command, entered my admin password, and what do you know? Friggin' Time Machine good to go again.
Excellent. Hope this helps someone else out, also. Thanks to OP and everyone who posted here!