I have a problem with one of these kits. Numbers 5, 24, 16, and 33 do not light up. 5 of these kits were built by Yr8 students and all others work ok apart from this one. I have checked polarity of LEDs, swapped the I/C with one of the working ones- still no luck, checked tracks and for shorts. I have also noticed that as the sequence goes round on pressing the button it runs 1, 20, 14 then 1 and 20 light again! Any ideas please before I loose what little hair I have left!!