Shepster had it nailed, the piping was not too bad, the leaks were coming from the grommets and fuel sender.

You can see where the leaking fuel has washed off the underseal that was applied to the tank.


Signs of leakage from around the fuel sender and gromments.
The grommets that I removed don't look too bad, I suspect that they were badly installed.
I have a load of photos and can write a small how to for the WiKi if people think it's worth it.
Cheers
TAD