The large round headlights are always like this:

black wire: ground (earth)
Red/white wire: one beam
Red/blue wire: other beam

They'll light up if you test wire them differently. You could hook + and - to any two connectors and some light should appear, but it will be dim if you connect high and low to the battery. So look on the 1200's connector to see which one is the Earth connector.

If you see black stuff inside the headlight the high beam may be burnt out.