Troybilt Horse PTO 4 Speed (1980s) - wheels turn but tines stopped

[MrBillbrown]

While I was tilling with my Troybilt horse, the tines all of a sudden stopped tilling. The tractor still works fine in all gears. In troubleshooting, I noticed that the P.T.O. lever used to engage/disengage the tines attachment moved without resistance. I detached the tiller attachment from the main transmission and I didn't see anything obviously broken.
When I turned the dog clutch on the tiller attachment by hand, the tines turned so I assume that the gears are not stripped. On the power transmission side, the dog clutch turns when the tractor is shifted in forward gear, so I assumed that that part is fine. What I am trying to understand is how the PTO clutch is engaged. The PTO clutch level moves fine without any sloppiness, but it's not clear to me what the lever pushes/moves to engage and disengage the tines drive shaft. There doesn't appear to be any broken or bent parts and no adjustments possible.
Can anyone tell me how this works and what may be causing the tines to not turn? Which of the 2 clutch dogs move to engage the tines (power unit side or tines attachment side)?

 

[hotrod351]

the tine lever pushes out the cogg on the back of the transmission to engage the cogg on the tines.you should be able to look, or feel, the cogged piece sliding out and in with the tines disconnected form the trans. you might have a broken wood-ruff key. #34 is the piece that engages and it has a woodruff key.