So far I have sent Post Cards and Yellow Letters, and I have used Facebook Ads to market to the zip code I am currently targeting.  

Take note of the attorney(s) name on the probate calender has he/she could be representing different estate's but they are at the hearing for a (different) reason.Also listen for competing (2 different attorneys) probate case #'s but same decedent..Couple of examples at a probate hearing; Appearance is required for hearing on trust petition, Missing original will, Missing sufficient publication, Missing sufficient notice to (heir with interest to property) etc; etc; Be on the lookout for PR's that are being self represented (in pro per) for the estate..These examples are based on CA law (probate code) and Lafi is correct, the more difficult to gather leads the less competition...

I also could call the animal control people (I believe it's actually against code to let cats roam in the city - though nobody tends to enforce it), but that probably won't endear me to my neighbors much.... 

Check your housing code chances are your housing code will say you provide them, ours does.

Would you ever do a number pad lock and just change the code between tenants?

They verify that the properties electrical meets code and it is on record that it is a rental. 

I can also update the statuses of the deals (color coded) so they can see what's going on.

There is another franklin street in the city so they probably got the zip codes mixed up.

My suggestion would be go to meet ups enter zip code 53210 and maybe go out 35 miles.

It should be fairly simple for a contractor to put in a to code vent if you are not handy.