Polaris Secondary Clutch

How does the secondary Clutch work? Im working on a 400 scrambler. At idle it wont shift into gear, just grinds. If you jam it in gear real quick , it just kills the motor. I took off the cover and jacked up the quad. With it running the primary clutch seems to work good. At idle it opens all the way up. Does the secondary clutch have some sort of way to release so when at idle the tranny isnt running, so it will shift?

The quad had set outside in the weather for 2 years.