Worn pump flow control valve and bore allow pump pressure to leak to low pressure side of pump.
Ream the bore to restore circularity and size the diameter to establish functional clearances between the reamed bore and oversize valve. Functional clearances will eliminate pump pressure loss and slippage.
In Nissan RE0F10A/Jatco JF011E units the pump body flow control valve bore wears due to constant valve movement. Poor preventive maintenance practices can contribute to excessive particulates in the transmission fluid, leading to increased wear of bore walls and valve spools. Sonnax oversized pump flow control valve 33510N-01 reduces valve spool wear through the use of hardcoat anodizing and by extending the length of the valve a little to spread any sideload forces on the valve over a larger contact area.
A vacuum test at the port indicated fails to hold at least 14 in-Hg.