Andy In Grahame’s photo just visible I recon can see hole in the thread towards its end, I have seen all these sort of things bodges get up to, like a nut coming loose so they found one with a tighter thread being a different thread rate. Going back many years the one of the engines I had was a bit flat for some time but always started and checked the timing think 30 degrees BTDC if I remember right that didn’t improve things, then changed out the complete unit, only difference was the points, seems a bit odd as complete arm made of Tufnell used a flexi wire from coil and the stationary point was earth, whereas all the others have been opposite so stationary was insulated and fed from coil and point arm had just a fibre heal rest all steel earthed through the spring so less likely to fail, well it worked.
