Preheat a little less and remove from fluid bet a little quicker.
Less heat and less time in the fluid bed should leave less paint on the head. This should keep paint from pluging eye of hook.
Only need enough heat to make powder stick to head.
It will look dry, no gloss.
A quick reheat will smooth out paint. Then bake.
I do #4 and #6 hooks with no paint in the eyes this way.
Hope this helps.
Garry.