Ben, the PTO is engaged by a spool valve covered by a rubber boot on upper right of MCV.
Reference 784 MCV parts diagram.
1)Bottom left front Items 4-12is Power Steering, Oil Cooler, Power Brakes outlet and relief valve at 1500 PSI, item 1-3, 13 are priority valve that diverts 3 GPM to PS,PB and Oil Cooler.
2) Item 39-42 is main relief valve at 2500 PSI
3) Items at top right are to do with PTO.
Not shown is 3PT pressure and return connecting on back right.
I still believe that somewhere the Hytran is bypassing the pressure lines to the PS,PB and 3PT and wherever the bypass/leak is by reving the engine there is enough flow to operate the PS, PB and 3PT at reduced capacity.