Unfortunately, one of the captive nuts welded into one end of the crossbar had a bad weld that impinged upon the thread area. The result was that when I tried to screw the bolt in, it seized. I had to use a pipe wrench on the crossbar and a 4-foot breaker bar to unscrew the bolt until it completely seized and I twisted its head off. This messed up the cross bar (the pipe wrench crushed it) and of course messed up the bolt, but at least I got this mess off my bike. This is the best photo I have of the damage (click on the photo for a bigger picture). You can see the welded-in captive nut, and the crushed area where I held it with the pipe wrench, and you can see the head of the bolt that I twisted off down below. The bolt twisted off at a point within the captive nut where apparently a bead of welding slag came to rest and jammed up the works -- this wasn't a case of me over-torquing a bolt (the bolt would have broken off at the point where head and shaft meet in that case).
I will call Pat on Monday and see if he can fix me up with a new crossbar and bolt in a timely manner. Needless to say I was using the sort of language in my garage that is not fit for polite company. Especially since I had to take that blasted kickstand bolt off again and it was partially hidden by the skid plate, meaning I had to use a box wrench and very slowly one tiny bit at a time unbolt it, plus my garage was hot so I was sweating like a pig... so anyhow, my bike is unprotected again, stripped of all skid plate and crash bars. Sigh.
-- Badtux the Still-unprotected Penguin