Hi all, thanks very much for your replies - much appreciated. I've since been told that the offending item is a resistor, apparently the pink wire runs to the left-handlebar switch (which would tie-in with Dave M's note about the headlamp circuit). Have managed to solder the broken pieces back together but haven't tried making a container as yet, or resealing it.
Geoff; if you still have the same problem with your own bike, might be worth giving Dave Silver a ring. They don't have the resistor listed on stock, but they are generally able to source parts - the only reason I haven't done so is because I wanted to see if it could be repaired (and I don't want to spend loads of money on getting the bike running only to find the engine's banjaxed!) If our new-born ever sleeps long enough for me to have 'spare time', I'll try and get the bike running and report back on how the resistor is holding up from being re-soldered.
All the best, ride safely,
Rick.