In the attached schematic image, under normal operation Led's D808-D823 do not light up yet D806 & D807 do illuminate properly. Connection "C" has +5v and "B" & "C" are connected to a SPDT switch which is connected to ground. I have tested each LED and confirmed they are all working, drawing approx 1.6v each. If I power the circuit and ground any of LEDs D808-D812 they light up respectfully. If I ground any of the LEDs D813-D817 they light up respectfully and the switched on LED D808-D812 lights up. Nothing lights up if I ground any of LEDs D818-D823. How do I troubleshoot this circuit? And what is purpose of diode D825?