Recommend you take the property off the market, get another Plumber to test the system and diagnose the issues, fix the system, and then put the property back on market, and get it Sold. 

My brother in law was caring for my mom in law, she moved in with him when she was diagnosed with cancer, 6 months to live, he tried to move her to a medical facility, but died first due to the long waiting list.But both here and San Francisco, brokers would take down info needed to meet disclosure requirements, and my position is I rely on their expertise.

He diagnosed that the return pipe is blocked. 

There's other places to give it to that will also give you tax benefits.My father in law who was diagnosed with ALS thought the same thing.

We hired multiple contractors to diagnose but on one was able to give us a definite answer.

Because I have not walked, driven, and not worked for 9 years, and about 15 months ago my wife was diagnosed with terminal cancer and she had to move me into an "old folks" home right after that and she passed on in September and we managed to stay married and dealt with being separated. 

If they are asking about an emotional support animal, then they have been diagnosed with a mental condition by a licensed psychologist or psychiatrist...from your state, and can supply the appropriate letter of diagnosis. 

I am thankful for all of them.Secondly, having escaped the Soviet Union, and having been diagnosed with MS and told that by now I'll be in a wheelchair, the idea that I live as I do is almost unimaginable. 

Hard to diagnose over the computer but hopefully that helps.

I'm fortunate to have a very mechanical background with decades of housing experience so I can generally diagnose a situation pretty well before we spend money.