Question about Atomic machine

Hello... I have an Atomic machine that's old but in great shape. I tested it and it seems to brew fine, but I have a question. Looking into the water fill hole under the black knob, there is a small hole in the aluminum riser tube. The hole looks out of place, but it appears very round as if drilled, vs. from decay or damage. Can you experts confirm whether or not this hole should be there? Thanks.

From the master of the Atomic: Frederick Nakos!

"Yes it SHOULD be there.

The Atomic is on the ring of fire: electric, gas, petrol, wasted uranium....what have you and the water starts to boil, slowly at first...pressure makes this water go up the tube towards the group , that is where all your coffee grinds are waiting to be imbibed. BUT the water is not quite hot yet, the brewing temperature is around 200 degrees F, the pressure is not quite right.
It will attain 25 PSI.... Soooooooo the hole permits the quite not ready water/vapor to flow back into the bottom tank. When the pressure is okay, it will bypass this hole and reach the group.

By the way the Atomic is a sand cast affair so the bumpy texture inside the neck is aluminum, not crud.
Enjoy your Blue Mountain."