Yes! I have suggested this and it seems the plumber that comes here doesn't even want to go under building to check pipes, upstairs to neighbor whenever it is suggested. I get a "no" when i suggest that the stack pipe may be the problem. I dont understand why?? Any plumber I've ever seen work is checking the whole house when they arrive?? Either this guy is milking the co op by visiting and then "we' the shareholders are getting remarks from management like "you can't keep calling the plumber every time your toilet gets clogged! Later for them...happens again im calling department of health, or the state..