I e-mailed TT on July 2, and got a quick reply. They asked for a list of exactly the bits I need. They now have the list, and I'm waiting to see what they will do.
My guess is the PO bought the rack secondhand, and none of the nuts/bolts/spacers got passed on. I would not have noticed, except that one of the Pelican cases and the side rack had to be bowed about an inch to mount. I figured something was wrong, so I started checking into how it should be installed. I don't think the case would last long in service warped like that.
I like it that the Motech installation instructions are on the web and give a thorough parts list. You can replace a lot of it with off the shelf metric stuff, but the spacers are custom, and at least one bolt is not at my local hardware stores.