It's a touchy issue because it is a health hazard, abatement is expensive, and "professional tenants" really mar a genuine issue.

Full disclosure, I have a background in mental health and addiction treatment so I may be in the minority here.

“Its for ventilation, for good health!”

No response.The 15th comes and the husband says he has it but he gave it to the city because I didn't do anything about the mouse problem and he has called the health department and will be calling the news.

Finances aside, the cost to your health and safety if you don't do so legally is simply not worth it.  2.

Best to cover all your basis, this may be a health concern. 

In Beyond Pricing have what they call a health score that helps you to gauge the performance of your unit.

The tenant essentially has only the right to health and safety and that is it (and deposit back after within 30 days).   

If it's taking time, or if there are/were potential health risks involved, the tenant has a point. 

Non-qualified period can be ignored if the period of temporary absence (not to exceed an aggregate of two years) is due to change of employment, health conditions, or such other unforeseen circumstances as may be specified by the IRS.