Often if the LEDs are all on the time, it could indeed be corrosion inside the red plug that plugs into the back of the pod. And/or corrosion on the 7 or 8 Pins on the pod itself.
Also could be dry solder joints on the pins on the pod.
What i do is remove the pod, unscrew it to get inside and then try inserting the red plug onto the pins but from Inside the pod (the pins are very long). Usually the pins on the inside of the pod are clean so you can do a test this way.
I then clean the red plug with a tooth brush and suitable cleaner (nothing that melts plastic), then dremmel with a fine wire brush the pod pins.
This has worked for me in the past. Otherwise it could be anything really (pod, red wire loom/control box) if you have access to a spare pod then try another pod.
posted on: 11/10/2013 15:40:06