Briggs not charging battery

Hi All, New to the forum, and looking for some help.

I have a Ferris Pro s with a 27 hp Briggs motor. I bought it used and found it was not charging the battery. Started by changing the voltage reg. Nothing.
So far I have made sure the fuses are good, the battery is good, I have 12.5 dcv back to the reg. with the key on. On to the stator. I have just over 28 acv from the stator at 3500 rpm. Reading that I should have over 30 acv I replaced the stator. New stator puts out exactly the same as the old one. 28 acv. At full speed I get about 12.65 dcv to the battery. Not charging the battery. With the pto engaged it draws down to about 12.2 dcv. below what the battery starts with. I have two good batteries that I charge on my bench, and switch out until I can figure out the problem. still need to mow the lawn. For what its worth, I have had to replace the PTO switch. And also the unit was used with a snow blower. Next I was going to start chasing wires and connectors, looking for bad ones.

There seams to be a lot of knowledge on this forum and was hoping for words of wisdom.
Thanks Tom

New regulator, battery voltage to the regulator, and 28 acv lead to lead output on the stator, I would be checking the ground to the regulator housing. If the regulator housing isn't grounded it won't work. Without the engine model number I am guessing to what charging system you have on your engine. So also the wire color and what the connectors look like on the regulator and stator would also narrow down what we are looking at.