Honda BF8, BF9.9 and BF10 Outboard Motors Shop Manual., Page 366Get this manual
4) Push the "UP" side of the power tilt switch and extend the
piston rod fully
SEALING WASHER
5) Remove the special tool and pressure gauge from the valve body Install the sealing washer, manual valve and the internal circlip in the valve bodyCAUTION: Be sure remove the special tool with the piston rod fully extended, or ATF spurts outA small amount of ATF flows out after removing the toolInstall the manual valve quicklyInstall the sealing washer securely not to let it collapse in the valve body