If flow related try idling the tractor down. Functions should run slower but would be surprised if makes much difference in digging force. If it does then would look real hard at installing a larger tank line and or tank line connection.
I have a BX23 with correct BH and pressures.
When I haven't used it in a while, I wonder what has happened, and quickly relearn that it is me. After an hour or so, the BH is as strong as ever (when I have learned again where and what to pinch).