They said they will send someone in 2 weeks.I checked around the house looking for water signs of leakage.

Most significant are environmental issues centering around past or present leakage of petroleum products into the ground. 

The house just got foundation repaired, and obviously there’s a leakage at some point.

If you're coming in short monthly to cover these, identify where the "leakage" is. 

Ask the power company to evaluate for any electrical leakage that you can repair. 

Hi If anyone can give some adviceAbout 8 months ago in June 2023, tenant complained of water leakage in one of the rooms, I sent my handyman to take a look and looks like the HVAC air filter was completely blocked, it caused alot of water to leak onto the floor. 

Commonly, with multi-tenant buildings, there is some leakage in NNNs, even if it is things like tenant pays for maintenance contract on RTU and any repairs up to $5,000.  

If the town confirms there is leakage, you have to run the tests and do remediation.

More than four months rent were lost between missed rent payments and legal fees to evict the tenant.The next tenant was much better, but had frequent complaints regarding legitimate problems: -bathroom sink hot water knob that didn't work-rat urine smell coming from the vents-water leakage from the toilet(I understand that problems occur, particularly with properties of this age, but it was surprising/disappointing considering I paid Ohio Cashflow $64.9k for a property they bought for almost half the price, then, even after having done improvements, still required frequent repairs.)3.

More than four months rent were lost between missed rent payments and legal fees to evict the tenant.The next tenant was much better, but had frequent complaints regarding legitimate problems: -bathroom sink hot water knob that didn't work -rat urine smell coming from the vents -water leakage from the toilet(I understand that problems occur, particularly with properties of this age, but it was surprising/disappointing considering I paid Ohio Cashflow $64.9k for a property they bought for almost half the price, then, even after having done improvements, still required frequent repairs.)3) Property appreciation I bought the property for $64,900 and sold it for $48,5000.