New XMod - Reverse Not Working - Please Help

[kennylxix]

I hope this isn't a common problem that I just managed to miss the solution to in my searching but here goes:

My buddy and I bought a total of three X-Mods yesterday. We put them together with various upgrades (bearing, awd, tires, etc...everything went fine but when we tried them they don't want to reverse. Forward works fine but it usually takes 5 or 6 tried to get them to reverse..they don't hum or try to work...just nothing until several tried later it goes. This really sucks because we can't brake...All three cars do this to varying degrees.

PLEASE HELP ME!!!!

Thank you!