Gravely pro compact 34 blades slowing down when i engage the hydraulics

[seedsofseasons]

I have a gravely 34 compact zero turn and it runs fine the idle speed is good even when the blades are engaged but as soon as i pull forward to cut the blades slow down. This is above my knowledge of the mower please help.

 

[bertsmobile1]

it should momemterarily slow down then the govenor kicks in and the engine should return to proper speed.
This is assuming the engine is running WFO.
Check the govenor & linkages.