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For the moment, put something between seat and back deck-battery box. There is a LOT of leverage on that seat stop point. Once it bends or breaks, repair is difficult.
There are a few suppliers (Ecklers, for one) that sell seat bottom repair plates for around 25 bucks. The seat needs to come apart to weld the repair plate on. Since I've rebuilt my seats my drivers bottom has also broken after 10 years. Time to either make a new plate or buy one.
Good luck. Don't get a butt splinter from those wood blocks!
Stump
If I am understanding the issue, I think I fixed my father in law's seat that had the same problem in the following way-
If the welded nut on the inside of the frame came loose all you need is 2 nuts (and 2 washers maybe) to make it work and look halfway normal.
Just think of the bolt going through the frame and the 2 nuts pinching the frame - one on either side of the frame.
Start with one nut on the bolt all the way down by the rubber. Put it though the frame then put the second nut on. Get the bolt in the position you want it and run both nuts up/down the bolt until they tighten against the frame.
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