might have just had a bunch of pinch, so warming it up let it expand, good sign that lots of life left on the engine though. really glad you got it going! need more nitro burning going on in the world!
as far as the metal shavings at the starter plate, and then running afterwards, i am at a loss on that, maybe double check what the exterior of the backplate looks like if it looks like it had some scraping goign on or something. might remove the cooling head for peace of mind, but if you are...