Thanks all - I didn't realise I was starting such a debate

It's got a brand new fuel line (yes, braided hose) onto the tank, but I'll check it. It was fitted about two years ago when the chassis was replaced, so Ken will know better when that chassis was delivered

So - it sounds like a trickle is expected when idling, but not that the fuel filter should empty when left over time. My drummer will reprime itself (it has a new pump on it) if I churn it ove for long enough, but the orange one will have none of it.

I'll try blowing into the filler and see what happens.

Thanks again, Ben