UPS did not stop at my house Friday, so results will have to wait until next weekend.
I did pull the air meter out and take pictures.
The first pic shows the potentiometer housing mounted on the air meter. To remove the housing, put the tip of a knife in the middle of the cap (1) and pry out.
Then remove the four screws with a T15 torx driver. -right pair shown in (2)- .
If stevebfl will confirm, I think the cap on the outside with the trim screw underneath is (3). The rubber cap did not come out intact on a 15yr old version, hopefully it will on a new one.