I recently acquired a used WD45 manifold from Andrew Kimbrough - the one on my tractor was pretty well toast - had two large cracks in it. Finished installing the new-to-me manifold this morning - fired up the tractor and all seems well. It's lost several of the symptoms that I thought might be associated with having a cracked manifold on there. I did a check with brake cleaner and had no change in rpm. Great to be able to put a good used manifold to work! Also appreciate the  great job Andrew and his f-i-l did getting it to me.