MecSam

First off, hi all! First post... I recently bought a DT 125 R on a 51 plate, and have been using it for a couple of weeks, runs nice (only 9000 on the clock) and generally no problems at all. However, I have started having to make reasonable trips during the night for work on it, and the lights are well... rubbish. The headlight doesn't get bright untill I am reving into the 5-6k range (although usable most of the time), and then when slowing for a corner, the headlight dips, brake light then dips it some more, and if I need the indicators on, I may as well have switched the headlight off! I believe the lighting system is all original. So my question is... can anyone suggest/help/advise me of a course of action to improve the situation. Cheers Sam