Honda BF8, BF9.9 and BF10 Outboard Motors Shop Manual., Page 346Get this manual
6) Remove the spool valve cap using commercially available driver bit 2.8 mm7) Apply small shot of air pressure to the oil hole in the spool valve cap to remove the valve 6.Remove the valve from the spool valve cap8) Remove the O-rings from the spool valve cap and valve and discard themReplace the O-rings with the new ones during reassembly [I] SPOOL VALVE CAP