I'll tell you now THERE IS NO POINT IN LOWERING THE MILEAGE!
The bike is a 1992! These bikes are not dropping in price anymore. If anything they're just increasing. Whos to say that that is the original clock? Really doesn't matter nowadays. If you buy a DT you buy it because you want a two smoker. You know what you are getting. A full service history is all you're going to need and you'll still get $$$ for it!
heyyyy the bikes a 91 with 21 k im not worried about mileage cal more worried at night i only have the oil main bean etc lights working cant see speed or revs lol hence only thing it can be is bulb issues ?
the bulbs are in rubbers at the back are they not just pull out ? even if not dont split the clocks just drill a hole to suit a size of 12v buld or led of any color and insert in to hole seal with some silcone and hey presto job done