TEF 20 leaking transmission oil and PTO lever disengaging

[French Fergie]

Our TEF20 hit some wood in th long grass this morning, the TEF20 stalled. On starting up again I noticed a signficiant leak of transmission oil from the PTO shaft. I engaged the PTO lever to test the PTO. As soon as the cutter engaged resistence the PTO lever popped out. This repeated a couple of times and the leak persisited.

See video of damage here.

Before I dismantle the system, is there anything I should check first?

 

[French Fergie]

Update - The shaft will come out about 4" but no more. The seal and and split have come out. Can I simply replace these and avoid splitting the tractor?