There are usually two springs pulling in opposing directions, but only one is visible in your picture. However right at the top edge of the picture I seem to see the bottom hook of the other spring, not connected to anything. Perhaps it should be connected to the center hole of the pivot-plate at the top of the picture? Dunno, I've never actually seen a Quantum XL50, and your picture only seems to show the bottom half of the governor.
You should be able to move the air vane with one finger and see the governor operate. You should also be able to see the change in operating pressure for the vane, as you advance the speed control.
If it is a two-spring governor and one spring is disconnected, the engine is likely to over-rev in a big way.
