Other than that, a refrigerant leak, the fan motor burns out, just throw it out and get a new one.

This later confirmed why the toilet was leaking and needed to be reset in the first place -- they had 3 kids so I'm pretty sure that had a lot to do with it.  

That’s step 1. step 2 - contact a local commercial broker and ask what the avg cap rate is in the area for SS units. step 3 - use the cap rate the broker provided and the NOI from the docs the seller gave you. 

Or I could dig up an irrigation leak, zero knowledge required.

Ridge Lending All in One, first position HELOCAmericafirst 80% LTV on noo 65% LTV UtahArvest Bank AR, OK, AL, MOBank of the westBB&T will loan on a rental portfolio, tooBBVA CompassBoeing employee credit unionCalifornia: Cal Coast Credit Union and Fremont Bank.Citizens first position HELOCCMG a financial 70% LTVEast West Bank, up to 60% LTV with "no docs”Figure 80% on a rental, not in LLCFirst Florida Credit Union https://firstflorida.cumortgagecenter.comGreat Lakes Credit UnionHSBC 70%, for premier clients onlyHuntington 75% LTVHurst Lending and Insurance Investment property HELOC in Texas.

One, expected, but arose sooner then expected, was re-piping the house due to the old galvanized pipes causing low water pressure & continuous leaks that were needing to be repaired. 

Typically 30Y fixed, refi into an LLC, low doc loans that don't report on your credit. 

When rehab was done they would do a 442. and boom docs to escrow within a few days of the 442..

I have a few questions about handling this situation:- should I hire and pay for a plumber to go into their unit to cut open the ceiling and identify the source of the leak? 

I strongly recommend not getting a refrigerator with a water hookup they often leak and damage the floor or the downstairs unit or attract mice to the source of water.