Spring for cowl vent damper?

[Stocker]

Curious about the small spring shown in this pic by CUSTOM/10. It appears to aid in opening the damper, but the vacuum servo does that without any help from the spring. When the servo closes the damper, the spring actually works against it just a little. Could it be a backup (failsafe) in case the servo didn't work at all, to open the vent allowing fresh air into the cab? Or does it have some other purpose?

I borrowed a spring from one of my gate latches to see how it worked. If that spring needs to be there, the hardware store probably has one. If it's not really needed, I can put the cowl back on and call it a day.