this is a big problem with modern pens but if the feed is ebonite the channels should be carved out deeper to keep up with the thirsty nibs. i dont know why they don't come this way to begin with. it seems odd that we can't get good modern flex feeds when the old ones are all in the public domain now.
The noodler's pens actually come with a sheet showing you / telling you that you can carve out the feed to make it wetter if you need it.
I'm about to throw a Brause Rose flex nib onto my ahab, so I think I'll probably need to carve a few more channels.