RE: Old OS .40FX will not fire
Take the HSN valve completely out. Put your finger over the muffler outlet and turn it over with the electric starter. It should spit fuel out where you took the needle valve out. IF not, then it is gummed up in that area. Side note make sure you don't have the glow plug connected to make it hot when you put the electric starter on. You are not trying to start it, just cleaning out the needle valve assembly.
Good luck