Thanks for that question Bobby...I was wondering the same thing and was not sure if those guards I see were just for the spring or to guard against all the moving parts as well. This unit came with a crappy full guard in place, but we were considering bolting on a simple circular plate in front.
Alternatively, if a guard were just intended to prevent a spring flying...could one just insert a longer bolt on the right hand side (see me second to last picture). The bolt of course could not go all the way across, but maybe long enough so that a dislodged spring could not get away.