J_DT50

Just imported my 2005 DT50R from the continent and getting ready to register it here in the UK. I've tried fitting a new tail light to illuminate the reg plate, but thanks to the stupid design of the original number plate holder, it lights up the back of the reg plate - very helpful! Any ideas on where to get a decent setup? Secondly, after fitting the current light (and having the bike trailered to the UK), the digital speedo/clock/computer is very faint and the clock is counting through the time like there's no tomorrow (literally)! I've checked the battery (all fine and charging "in case"), and disconnected the new light to eliminate what I can - no change. This is a big pain at the moment, as I need to use the bike ASAP! On a minor note, is there a way of switching from km/h to mph or do I need a new computer? Thanks in advance!