Scag Walk-Behind Peerless transmission problem

[Crystal Lake Lawn Care]

Hi Everyone! (new member - first post)

I was mowing with my scag w-b with the peerless 5-speed transmission, going up a slight incline in 2nd gear, and suddenly the whole mower started shaking and making metallic grinding noises in the transmission area. Shifting into other gears didn't help so I just shut it down. I restarted it and also noticed a slight knocking noise coming from the transmission input pulley/blade clutch area.

Any advice or help pointing me in the right direction would be appreciated. - Erik