No Dipped Beam

Hi
I have a 1997 300tdi Defender, tonight I have completely lost dipped beam, but I still retain side lights and full beam. Several years ago I had a similar problem which turned out to be the master light switch on the columnn, However after taking the switch off tonight the switch seems to be ok, unlike last time when it was clearly worn. Any ideas what the next thing to check is ?
Thanks

I've also had the same problem twice... broken wire on the switch both times... you've checked that so... what about the connectors behind the headlights? or try to run a continuity test from switch to lights?

Hi
The switch seems to be the most likely cause, so I shall try a new one tomo regardless. I am no expert but I have run a feed direct from the output of the switch to the dipped beam feed from the fuse box and both outputs from the switch (red and blue cables) and they both operate the dipped beam. I've tried refering to wiring diagrams but in the inclusion of the dim dip system seems to really complicate matters. My brain hurts.