For reference I threaded a 3/8” NPT tap into a fitting hand tight and the depth engagement is 5/8”. Even with a shortened tap this is mighty invasive in that location. As for EDM its crazy slow and expensive for me when I need it. A 1/8” drill costing $5 broken deep in a part can cost me $600 to remove so even slightly worn tools are relieved of duty. Solenoid housings in the last picture require 17 press fit expansion plugs to direct hydraulic flow.
