Have used a Paasche VL for over 25 years now both professionally and for my Hobbies , from 1/144 scale planes to full size Dinosaurs , blown everything from oil based to rubber cement based paints and it never fails

The needles have small rings or grooves at the back (non-pointed) end. One ring for #1, three rings for #3, five rings for #5. Also, my #1 does not have a shoulder about 3/4 back from the pointed end, while the others do. The shoulder on the #3 is about 1/16 farther back than for the #5.