Info and how to go about getting the root problem, the foundation, corrected would be greatly appreciated. 

Hey everyone - I'm James, primarily based in Austin, TX with roots in Northeast Ohio.

With all the mature trees nearby, you need to determine where the sewer line runs, and scope it for roots or other problems, based on the age of the unit.

The root cause of unaffordability in this region isn't high rents — it's not enough options.You can't solve a supply problem from the demand side.The MisdiagnosisRent control is the most popular proposed solution to New England's affordability crisis right now.

If there's a blockage or a tree root growing through the sewer, the water will start to backup, indicating a problem with the sewer. 

What I might do is include your receipt from the snaking in the lease and have the tenants initial it, acknowledging that any future drain issues will be charged to them (other than tree roots).  

We are rooting for you. 

Compare the joist heights and you can probably see the root cause of your sagging.

I am a numbers person, but I actually prefer more simplistic analysis rooted in current/real world numbers.

I have roots in both countries and wonder if anyone living in the US is buying property in Australia or if any US expats are investing back home.