Had a nice day to work in the driveway, so I went to Home Depot to pick up a few repair parts.
I got a 3-pack of quick links. I replaced the broken side, but did not replace the opposite side. I know that some people have done it pre-emptively, but I figure right now "if it ain't broke, don't fix it." If/when that side breaks I have the parts to fix it.
Note: do not wear a watch, it will get in the way when you are trying to reach the lumbar button from the back seat. It also gets in the way when reaching under the seat to unhook and reattach the elastic that holds the lower flap of the seat back panel.
Step 1: Trace the elastic band underneath the seat that connects to the lower section of the seat back panel. It helps to raise the seat up as high as it will go. It's hard to see under there, and there are some sharp edges. Be careful. See my picture of my injuries. Also, make note of where that elastic is hooked so you can put it back in the same place. Unhook the elastic.
Step 2: pull that lower flap back and you'll expose two screws. Remove those screws, then pull back towards you on the lower part to unhook the lower part of that panel. Then pull straight down.
Step 3: remove the broken piece from the seat frame. I used needle-nose pliers for their reach. There will be a plastic grommet, it just snaps in and might come out when you remove the broken clip. Mine came out with the clip.
Step 4: remove the double stick tape and save it.
Step 5: thread a quick clip through the grommet and then put it all back into the seat frame tab.
Step 6: hook then end of the cable onto the quick link and screw the nut shut. I didn't torque it down, I did it finger tight. This will be easier if you release the lumbar tension by pushing the button on the side of the seat. You'll get a lot of extra cable to work with.
Step 7: replace the double-stick tape. This tape and the grommet prevent metal-to-metal contact and minimize rattles.
Step 8: replace the seat back and screws.
Step 9: Re connect the elastic underneath the seat. This is harder than you'd think and where where I cut myself a couple times without realizing it.
Total cost: $4.17 in parts, plus two bandages.
Total time: (?) not sure. Maybe 15 minutes total to remove/replace the seat back. Maybe another 15 minutes to make the repairs.
Edit:
I noticed the pix are in reverse order.