Brushless help!!

[benl]

Hello Chaps,
I recentley became the rather proud and excited owner of a second hand B4 complete with an LRP SPX stock spec and LRP X11 8.5 stock motor .
I was hoping to have my first day of racing tommorrow (actually later today) at TORCH.
Everything was running fine until this afternoon a quick test blast on the track outside my house and eveything ground to a halt.
The Motor only spins up occasionally now. It seems I have to manually turn the rotor to the right position to get it to engage which then works but stops as soon as I apply the brake or lift off the throttle.
I have checked the speed controller and all the lights are good etc.
I dissmantled the Motor and the rotor seems fine. Sensor wire looks ok etc.

Anyone got any ideas, any help at all would be appreciated
Thanks
Ben