I believe D4 and D7 are defective as I measured the voltage drop across each LED and found the drop on these two LEDs was much much higher than all the others (about 4v vs 0.8v on the rest).
So I am trying to find the correct replacement LEDs, but I don't really know how to determine the correct specifications. I thought to measure the power being supplied to this board, which came out as 12.4v on open circuit and 19.3mA short circuit (there is no resistor on the LED board so I assume there must be one in the board it is connected to).
Anyway given there are 9 LEDs in series, with a 12.4v and 19.3mA (short circuit) supply, is there any way to determine the correct LED specifications? Or are there any other readings I can take to try and figure it out?