Here is a picture of sprocket setup, as it was during teardown.
Notes: 1. The "chain adjuster" for the "blade" chain has slipped out of place, it should be up the other way I think. (above the chain pressing down) 2. The dog clutch fork is not correctly mounted on its pivot here. 3. The idler sprocket is missing here. You can see the elongated mounting hole just below the exhaust outlet. 4. There are 2 chains missing here, one from the small cog on the blade sprocket -> the idler sprocket, and one from the idler sprocket to the dog clutch sprocket. 5. Dog clutch "collar" not shown here.
With the engine running, engaging the main clutch causes the main drive sprocket (small one at the top) to turn, this immediately starts the blades spinning. This also starts the idler sprocket set to spin and in turn causes the dog sprocket to spin. The dog sprocket spins freely on the roller shaft though, the rollers only turn when the dog clutch is released (hand lever on the right handle), engaging the dog sprocket with the dog "collar" on the same shaft.
