Hi Kupu,
The extrusion was from the anti friction cap on the 420 poppet hanging up in the body, I actually have it in an AIR 1 with the little plastic cap removed while I wait for time to turn it down more.
I only tightened the nylock nut to about the same place it was with the stock seat. Another issue for the AIR1 is the height of the poppet at the nut end, I did modify the spring adjuster by cutting the nipple end off and sealing it so I can get full opening, not wanting to modify the poppet was my concern at the time but grinding the top down will be a better solution once the poppers become more common.