Account Closed PMs don't exactly have a huge incentive to refer properties to new owners unless they're getting to keep the properties under their management. 

So I'd recommend the following: 

1) Refer as much business to PMs that you can before asking for anything. Giving people referrals before asking for them goes a long way.

2) Once you do ask for referrals, let the PMs know that if they refer you anything then you will continue on with their management. 

3) Ask the PMs who their worst/most difficult owners are (i.e the owners who don't want to take care of their properties, fight over small repair invoices, etc) and see if they will introduce you to those owners. 

Most businesses want to get rid of their most difficult customers and PMs are no exception. That can be a win/win for both you and the PMs.

Account Closed there are commercial level PMs that you could connect with that may have more of the product that you're looking for. 

There is one in my market called Southern Development Management Company. I believe they manage several thousand of doors across the Southeast (i.e. 175 unit building with a couple of on-site staff, maintenance person, etc). Very professional and expensive. Twenty units is probably too small for companies like them but they have some in the 50-75 unit range.

@Account Closed I think it might be better to find other investors and just go off their PM referrals.