Your photos are excellent Paul, much better than mine. The old pin is made from a steel alloy, not an aluminium alloy. Alloy just means mixture of metals, and the steel in your original pin may be an unusual one. It seems to have a ground finish, not a turned finish, and if that is correct, it would be difficult to make one at home from the correct alloy. It looks as if making one of these pins from a material similar to the original, would require doing the job with a toolpost grinder. Cutting the circlip groove would then require something like mounting a Dremel tool on the toolpost and using a specialised ultra-narrow diamond wheel, or perhaps a series of ultra-narrow grinding disks. As it happens I do not have any such apparatus. The material itself could be 18/4/1 HSS (High Speed Steel), and could be obtained without serious difficulty I think.
Anyway, step one is to see if the one I made, fits and works. If it does both those things, the thread will contain useful information for other large OHV Tecumseh owners: the diagnosis, the drawing of the part, and the finding that the throw-away camshaft can actually be refurbished.
