The fix turned out to be easier than I expected. Pop off the two hinge covers, remove two small screws, the two T-25 screws in the center of the seat back, and the two 12mm hex head hinge bolts. Once the two bolts are out the seat back drops a bit and you can slide the plastic cover forward a half inch or so and remove it. Then there are some small metal rings that hold the seat fabric to the frame that you need to remove. I replaced them with zip ties. Once all that's done you have access to the latch. I was able to move the latch with a screwdriver and the release worked but was sticky, so I sprayed the latch with WD40 until it moved freely and put it all back together. And now my seat back latches in the upright position again.
Thanks all for the tips and links, you got me pointed in the right direction.
'04 Base Frosty, '08 Base Stealth, '05 Base Satellite