Stihl ms290 carb airfilter question

[Winmac]

Let me start by saying I'm not a sthil guy so I'm not familiar with em.
I was buying a 254 parts saw and the guy also had this 290 that was a not runner so I took a chance at 30$. It's looks good overall with little to no use and I did get it to start and run. Then I go to reinstall the air filter and see something that seems odd to me.
The vent tube from the metering chamber where it connects to the filter is not open, this doesn't seem right to me. Is it possibly stihl forget to open this? I can't imagine the saw could run properly this way.

 

[Winmac]

After a google image search it was apparent that the filter should have a opening, I used a dill and knife to open it up. I'll need to wait for the rain to stop before I can get out side to run it up.