727 front clutch testing

Putting my 727 together and went to air check the front clutch before putting it back in the case. Noticed it was leaking air by and not engaging the clutches. Found it Is blowing air out of a hole ok the back of the clutch drum I can cover the hole with my finger and it engages like it should. Comparing it to the front clutch in a 727 I have for parts that hole isn't there and it air checks just fine. and it looks like it may have been put there for some reason. Any idea on why it's there or is it a junk peice now?

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