I recently replaced the light bulbs as a previous owner had put the incorrect ones in which were drawing too much power (and touching the glass cover!). That seemed to have sorted out the cutting out problem, for a while.
Turning on the headlights with the bike running tends to dim the lights!
I can't complain too much, the bike is, after all, 20 years old. It's done me well and other than really really wanting to ride the bleedin thing on Saturday I suppose I can't fault it.
oh well maybe it's a sign....
kj