Toro 1028 Powershift Snowthrower

Help: no traction, no power to the wheels. (the wheels are pinned for power traction)

I removed the Auger housing from the engine frame and removed all belts.
The Traction Sheave, part # 62-1310 as shown in the Transmission Assembly Illustration is rotating freely!
No power transmission to the output shaft and chain sproket.

Do I have to open up the (sealed) transmission housing?