If you had an early collector was there a small rubber rod in the slit at the end?
If you had a later collector was the slit still held open with a heat weld?
If your collector fit in the barrel is too tight and the channel pinches shut, you get no flow.
No-no go gauge is used to test this.
The hole was in the long Aerometric breather tube to allow for pressure equalization in the ink sac when flying at altitude. The hole serves no other purpose per Parker. The long tube was chosen to allow the sac to fill all the way, when the pen was full and sitting nib up in your pocket and the plane went up (pressure down) you got a burp...thus the hole to equalize pressure.
But I am glad your pen is flowing nicely now.
Thank you!. Yes there was a rubber rod at the slit end. Also the collector wasn't fit very tightly to the barrel. It was tight but not super tight. My question is how is ink supposed to flow from the barrel to the collector, without such a hole? There are no slits or anything that would allow ink to flow from the barrel to the feed. The ink would have to literally climb on top of the breather tube to reach the hole that would allow it to get transferred from the barrel to the feed and then the collector.