Is there a ring gear anywhere on that motor?

No, that's the problem. The welder was manufactured without either a
starter or any provision to install one. Since I know old timers used
to start such welder by hooking the leads from a running one to the
leads of the one to be started, thereby motorizing the generator and
turning over the engine, it seems that using batteries to do the same
thing would work as well. Why would connecting the batteries to the
welding leads to motorize the generator constitute a dead short? Many
dc motors are run off batteries and that doesn't constitute a dead
short. What do I not understand about this?