Don Del - Just a quick thought, unsure of the weather in your part of the world but do you frequently experience Defender Footwell Flooding? If so, that might not all be entirely rain water. I'm guessing you've looked at the outside face of the footwell and there's no obvious trails that side.
It's just another leakage route that may not be immediately obvious. I mention it because I think my own clutch pedal is getting a weep from the master cylinder and I misidentified it as rain.