Hi,
A question about the guidance in this video.
Why would one need to do the air shot with the needle facing the ceiling? If the reason is to eliminate any air in the pen, then it never worked for me. Every time I tried to do that, there was still air in the pen. What I taught my child, which is probably wrong,
is to keep the needle facing the floor, not the ceiling, and whatever air remains in the pen, will always remain in the pen, and discard the pen when it is near the 20 unit mark.