Any one had any problems with the led display on these? Ive always had a problem with the 5 displaying properly. Originally when i flicked the switch on the middle line would be dimmer than the rest of the display. within 20 seconds though it would be as bright as the rest of the display. Recently though when i turn it on this paticular line is always bright and the problem has now moved to a different line that makes up the 5. I've tried different batteries but this line is constantly dimmer than the rest. I dont think the problem is anything to do with the contacts as the rest of the display is fine. Have i just ended up with a dodgy led? can it be fixed?