I'm printing one of these out now. Unfortunately all the documentation has disappeared from Adafruit's site. Can you tell me what size that screw is? It looks like it's in some sort of 'plug'- what is it? Is the spring necessary?

Also, do you use this for regular filament at all? Am wondering if I can just leave this on our Taz at all times, or if it needs to be switched in just for flexible filaments.

Thanks in advance!