Yep, agreed--they're a PITA! :badgrin:
And they do work best when they're almost closed (I used to be able to run mine about 40% open but that was the max...)
Also if you spilce an airline tubing valve onto the venturi tubing it makes them a little easier to prime.
(Then you just can just open/close the airline valve instead of having to yank the tubing off the collection cup each time you restart it.)