Symptoms have changed as above :-). Now I have no power whatsoever, and am at a loss as to where to go. I did as you said and have unplugged the headlights, as well as tried new aftermarket lh switchgear with no change

Cannot see where in earlier post you said that now you have lost all power, but if this now the situation, suggest you start at the main fuse located in the starter solenoid. Good fuse and connections then check that you have 12 volts at the fuse box when the ignition is on.

Post 5:-)

Right went through all the connectors and have isolated the non running to the female ignition connector - there's a bit of bunt-ness around the plug (hard to tell as it's black!) and wiggling the wires is what does it.

Now can there be something related to the h4 bulb, poss the left hand switchgear and turning the high beam switch on that would result in this connector melting? Or just down to age dirt and increased resistance that got worse when I had the high beam on?

Lastly - where can I get a replacement connector for this? Google is not helping!

The connector to which you refer provides power to most electrial units including the lighting circuits. It appears from your description to be in poor condition. The incresaed current flow when high-beam is selected will only make a poor connection worse, resulting in loss of power.

If you are unsuccessful in finding an replacement OEM type, why not simply replace the complete connector set with something readily available.

For OEM connectors, this place will have everything you need:

http://www.cycleterminal.com/motorcycle-connectors.html

Thanks luke! For some reason id looked at all the pictures and not seen it on there - click on the first one and voila!

Yeah I did consider just grabbing something from the electronic shop, i figure they use particular connectors for a reason though, keeps it looking oem and fitting in the little metal holder bit. Thanks though, hopefully it is the increased wattage of the bulb that has done this - though seems a little odd as no searches on here come up with others having problems with melting/corrosion of this connector.