My dipped headlight started to fail intermittently

My dipped headlight started to fail intermittently after I dropped the bike this spring. Took it for a service this summer and the report says there is an internal (dis-)connection fault inside the headlight unit and that this ''has happened before'' with other bikes. The unit is not servicable so the only solution is to replace @ 240.00 smackers + Vat + Labour + whatever you fancy. During my last East European trip all went well for the first week even though I had to thump the unit a few times to keep it working. In week 2 it gave up the ghost altogether. I have now taken the ''sealed'' unit apart, tested for continuity and found no resistance in any internal wiring. Noted however that the wires themselves were very stiff (sign of overheating?). The crimped connection on the 2 neutrals from the main lights seemed sound but the stripped copper tails were slightly discoloured. No other signs of overheating except slight discolouration on reflector of main beam. Connection to the unit appears sound but can't think of a way to test. Any ideas??