I broke my autosiphon by putting it together dry. After that, it wouldn't pull liquid up the tube to start the siphon. It was the smaller one, 5/16" I believe.
I replaced it with the 1/2" Autosiphon and what a difference. Man does it transfer fast!
Make sure to throw out the old one if you get the bigger one. It turns out the smaller cane can still start the
siphon in the bigger one but if you are racking a beer it oxidizes the everliving crap out of it. Not speaking
from personal experience but from being the guy that got the call, "Hey tell me if this tastes funny."