Repairing a J. B. Van Sciver Chair

I volunteer for an organization called the "Repair Cafe", whose purpose is to rebuff our throw-away culture by fixing things for people (for free) and thereby keeping stuff out of landfills. A client brought in an incredibly rickety chair that belonged to his mother. It wobbled excessively front to back and only a little less side to side. Usually we fix things right there at the repair event, but this one was going to need a workshop and some tools that I didn't have at the event, so I brought it home.The Van Sciver chairThis chair had an emblem on the underside of one rail indicating the J. B. Van Sciver Co., of Camden, NJ. A quick internet search found this company was in business from the late 1800s to about 1980. I'm not good at dating furniture, but it was all mortise and tenon construction and it used hide glue, so maybe it was made more than 50 or 70 years ago. The screws that held the seat to the rails were slot head screws, but they were clearly manufactured screws (not…