Water in boot coming through lights what do I replace

I have a 2004 micra that has wAter in the boot.
I have done a water test and it is coming through the lights.

Does anyone know what I need to do to fix this ? Do I need to buy a new light foam seal pad ?

It seems to be a common problem but know one knows how to fix it the only seal around light is the foam pad.

Please help.
IF it is the lamp seal, take the unit out and put vasoline on the seal.
Most likely it is the weld under the lamp unit that has opened up very very slightly. This is a known fault and it is easy to blame the lamp seal for the leak.
Tap the weld back and use a spot of silicone. That is what I did - problem solved.