Scag Wildcat, all motion stopped

[kennny1976]

Was mowing without any issues but then heard some clicking thru my ear protection. After a few minutes I decided to stop, disengage the blades and see if the clicking stopped.
It did. Then I tried to move forward and nothing...no motion, forward or reverse. I could re-engage the blades ok but no motion. Any ideas?

 

[MParr]

Check your belts first.