Definitely start with Tech and the scorers. At TWS, especially, bikes are scored from the front straight, which means the scorers are at an angle to the bikes coming down the straightaway. The speed of the bikes and the distance the scorers sit from the track can make for some very tough to read numbers if they are not placed correctly. The size (height) of the numbers is important, but in my years of working in Tech and working first-hand with the manual scorers (one of which was my daughter for several years), placement is also paramount, meaning the side of the bike the numbers are on (because "wrapping" them across the fairing means, perhaps, the number on the far side may not be able to be read), and the spacing between the numerals is critical.

This may also help: http://www.cmraracing.com/showthread...ht=bad+numbers