Our headlamps never actually fail once they've been successfully switched on, but they just don't always come on when requested. We've found that sometimes tapping the fuse/relay box or waggling the multipoint connectors underneath will bring them on and once they are on, they stay on - they don't suddenly leave you in the dark. But if you turn them off, they may or may not come on again. We suspect this is a relay problem, but don't know which relay controls the headlamps, or where to get a replacement. Any advice would be welcome. We have been unable to source a wiring diagram - again any advice welcome. Sometimes the horn also refuses to work, in sympathy with the headlamps.