Are you near Taunton ??

I've also cleaned all the threads and checked for damage to the filler valve and filler valve body threads and all appears fine, the seals are all new, I'm completely stumped, I guess the next logical step is to replace the cylinder and valve body and filler valve and refit new seals ??

Yes and yes

The leak is from the filler valve where it screws into the filler body, I have checked and replaced all the seals, I'm completely out of ideas

If the cylinder is flared would that still cause the filler valve to leak, I would of thought the leak would of been between the cylinder and the valve body?? If the cylinder is flared at the end.

Can you post up a photo of the cylinder and blemish, and why are selling it mate

Thanks I will try that.

I don't think so, but there is obviously something not right, is there a way to check the cylinder?

I've already done this but the leak is still present, any ideas

Do I need a special tool to remove the filler body?