LEDs are polarity sensitive. In short, unlike a bulb, they have a positive and negative side.
What I did when i got my leds was test them using a 9Volt PP9 type battery. Once they lit I knew which way was pos, and i scored a small mark on the positive side with a needle file.
On the PCB on the back of the instrument binnacle you can work out which is supply and ground. then you can fit the leds into the holder the correct way around.
If you want to avoid that process, just plug them in and if they don't work, turn them 180 degrees, but doing it this way means u might have to plug in and remove you binnacle a few times unless you're lucky and get it right straightaway.
You WON'T break them pluggin in wrong way
It's really not difficult and I will help anyone out local who needs a hand.
