Perhaps when they did the renewal of a line of credit for a business customer, they saw signs that the business might be heading South.

I'd give him notice that you aren't renewing his lease.

I did $90 increase the last lease renewal.

So, now if the other tenants are good tenants and you want to renew their lease they will be at ease knowing that theirs no mold there and would want to stay and the other tenant paid for it.

Your local law may say you have to offer renewal but it may not dictate terms so see what it says.   

Your main problem here is your own failure to raise the rents on every lease renewal consistent with, at least, inflation.

Those 3 tenants have lease renewals coming up.

They want to know their options for renewing and are concerned about getting an PITA roommate downstairs. 

So people are just now deciding to renew or look for somewhere else. 

Ask them when they issue distributions (anything before the 15th of the month is a red flag), do they require reserves, how is maintenance charged, do you see copies of outside contractor bills, do they upcharge materials (PM's have LAR accounts with Lowes and often get 20% off), do they keep all late fees or just the management fee, what other fees do they charge (renewals, inspections, etc), where are tenant security deposits held, how are evictions handled and are you consulted before filing, what screenings do they run, what qualifications do they require from tenants, ask for a couple other owners to visit with for a reference.