Anyway, he broke through the stairwell to access the second floor bath pipes and this is what the waste stack looked like, crack, hole and all. Right there in my wall was this time bomb spewing gas! Here are the rest of the pieces from the wall. Just look at that joint!
Jamieson to the rescue: he not only ran all the plumbing from the second floor to the third, he replaced the whole waste stack. I was particularly impressed with his labels. What a nifty idea, anticipating someone would have to tear out that wall again to access the pipes. It better not happen while I'm here, though.