Dellorto PHF32 A air passage question / Kara

Hi Everybody,
I have a Dellorto PHF32A that may have a blocked air passage. There are three air ports below the main bore on the intake side. The right hand passage as you look from the front is hard to pass air through. This is true on both carbs. Questions: What does this passage do? Where does it go? and how easy should it be to blow air through it?
Much Thanks!
Kara

Some PHF32 A (D) and PHF32A (S) from a 1977 Darmah are not drilled in the place you asked about.

Another PHF32 A (D) I have is drilled there but I can't blow through it. This is an unknown age.

Regards
Graeme

There's a manual covering the PHF here: http://www.iwt.com.au/private/Dellorto manual.pdf