I had to adjust the rain tipper screws a little bit on my Atlas also. It was reading just a little low. Afterwards, it's very accurate. The adjustments are very easy to tweak.
Glad to hear its adjustable, wish it was stated in the manual.
Yes...I could not find the information as well.
Is it like the 5 in 1? Are there screws underneath or do you open the hood up? I do not have the unit in front of me to see where the screws are. I did make sure the bubble is dead center when it was installed.
BTW, I installed in on my old 5 in 1 pole...distance is about 100 feet with a historic brick farmhouse.
From 5 in 1 manual:
"Be sure to adjust both screws the same amount. Turning screws clockwise will increase rainfall amount. Turning screw counter clockwise will decrease it.
Adjustment:
To adjust the rainfall reading by 2% turn both screws 1/8 of a turn.
To adjust the rainfall reading by 4% turn both screws 1/4 of a turn.
To adjust the rainfall reading by 8% turn both screws 1/2 of a turn."