Wedge lights

[mark350]

I bought my first TVR (350i) 1 month ago, before I bought it I checked that all the electrics worked, which they did, but now I have a problem with the lights! The O/S pops up, but N/S does not until I turn the lights off, then it pops up and goes straight back down again. I can hear the relay for the working light clicking but can not identify which relays to check...... Any ideas please. Thanks Mark