...in addition to my earlier email, it might be worth reading through this link ;
http://c5alive.co.uk/forum/index.php?topic=2151.0as well as checking a few other things by way of a process of elimination you'll get here in the end. To check it's not the motor brushes or dropped magnets try the following ;
Does the motor turn freely by hand in both directions ?
Does the motor run if directly connected to a battery ? To do this release the motor cables from the control box and place the cable ends directly on to the battery terminals. Make sure the necessary safety precautions are in place first ie wheel off the ground etc.
You also need to check the go switch is ok , can you hear a healthy click when it is pressed and released ?
Lastly, if after checking all this it all points to control box/pod fault then you could try radiomarty for check/repairs;
http://c5alive.co.uk/forum/index.php?topic=1083.0