Just adding a personal update from the problems i was having.
I ordered replacement parts which arrived yesterday. Immediately set about testing, and i was having the same problem as before. I tried all sorts of combinations of the boards and sensors with varying results.
I then got fed up and when i was trawling you tube i watched a few of the recent japanese videos, i noticed that r2 moves quite quickly, and this gave me an idea. I tried 1 more time with the replacement parts, moving my object a bit quicker - mimicking the rough speed on the videos.
SUCCESS!!
My blue light activates at 500mm ish. So i decided to give my original set of boards a try, sadly that was still the same. Swapped back to the new one just to make sure it wasnt a fluke, and it worked perfectly. So something was deffinately wrong with my original boards.
Thus endeth my drama and i am now a happy bunny.
Building:
Ghostbusters Ecto-1, Ford GT40, Gone in 60 seconds Eleanor mustang, Shelby Cobra
Complete:
R2D2, Red Bull RB7 RC, Battleship Bismarck, Shelby GT500 'super snake'