Thanks guys,
I haven't put a washer in, I think it is just the angle/light. I sent Derek an email; hopefully he'll make it all clear tomorrow.
It's been a frustrating day and the missing parts don't help. I haven't even got a manual yet - they were out of stock (2 weeks ago) and sent me the version for the 160 so I am working from that and the online version.
I know all my frustrations will disappear once it's on the road. My neighbour has just put his Caterham back on the road and took me for a quick spin yesterday. I loved every second.
Chris