I really doubt it is the feeder. It looks like a disease to me. The swelling is caused by a nasal infection.
If your birds have other symptoms that may help narrow down which disease but it is really hard to figure out what disease a bird has. It is usually cheaper to just start over.
If your birds have other symptoms that may help narrow down which disease but it is really hard to figure out what disease a bird has. It is usually cheaper to just start over.