I have used 3 options:
1) 1/4" drive hex socket with PH1 bit, approx. 42mm OAL
2) above PH1 hex bit alone, approx. 25.1mm OAL
3) 90 degree offset specialty phillips head driver (I don't recall the dimensions)
There's not much room to work, however then again, the balance screw gets turned very little.
Access is from the port-side only, as the oil pressure sender blocks access from the starboard side.
