All four ash-seat chairs were loose in every joint (that’s 22) between spindle and seat and spindle and crest.
The side spindles were screwed in from the side, wedged from the bottom.
This seemed like a pretty straightforward repair: Remove the back, clean the joints, reassemble and clamp.
Those little screw heads? Not at all! They were a cheap trick: 6 penny box nails filed with a screw-like slot!
In order to get them out I had to dig. I rebored a 3/8” hole afterward and inserted flat grain plugs I cut from similar ash.
In this process I discovered there was one lower side rung missing. I found a piece of maple to match, tablesawed it square and rounded it with a 3/8” RO bit, tapered the ends on the edge sander and banged on it a little for some scratches and dents.
The maple did not want to darken much, even with the nearly-ebony material I was using, so I built the jig shown and just kept sponging it on and brushing it out to prevent runs. Overnight it dried, and the look was right. Two coats of varnish followed, with steel wool to drop the sheen a little. It’s in the second picture with the jumble of parts. Where’s Waldo?
-- "...in his brain, which is as dry as the remainder biscuit after a voyage, he hath strange places cramm'd with observation, the which he vents in mangled forms." --Shakespeare, "As You Like It"