Pneumatic questions, sorry!

[Max]

Hi,
What kind of springs do people use to stop their QEVs misfiring when the gas is dumped? Where can you get them from?
As I see it, it has to be a very weak spring which compresses down to virtually nothing.

Also is there a reason my 5/2 solenoid valve seems to get stuck in the on position when I have the bottle turned off before a flip, I then have to put my thumb over the port where the gas come out for a while until it flicks over to the off position.