Just a follow up if anyone is having the same issue. I had this serviced at a local shop while I was deployed and they said it was:
The pto shifter had been pushed forward to far and came out of the bracket it rides in. they set it back in and recommended we build a bracket from the floor board to prevent the shifter from moving that far forward. They said if it does come out, it can sometimes be put back in immediately but the catch mechanism can slide forward preventing it from reingageing. No parts replaced, except for gaskets. They removed the rockshaft housing and put the shifter mechanism back in place.