Heater Matrix Bleed Screw JHN100010

Does anyone know the size of the heater matrix bleed screw? Mine is knackered and has been replaced by a solid bolt as a temporary measure. Everywhere is sold out and I've been told it's out of production. I'm looking for a suitable alternative if anyone has any ideas!

from the last news http://ift.tt/1coUYqk

via IFTTT