just installed BL-WOW-now problem

[tha5150]

just installed the BL power for the first time in my 3906. MMM + 8XL. :D everything was fine through 2 sets of batteries. 7 cells then 6. huge diffrence in the 7 cells, HUGE. so i waited a few hours, played some GTA 4 and charged the 7 cells up, swapped the tires for dirt from street and took it down the road at the construction site.
20 min into my play time truck just stops. jerking but no movement. forward and reverse act the same. here is a small video, from my cell, sorry for the quality. but PLEASE help me out here.
i installed the idler gears from UE so i know thats not a problem.
as you can see, i can turn the spur gear 360 degree's but then stops. this is annoying and i am not sure if this is a problem or not.
there is no radio interferance. batteries are all full, even radio. so there is a problem somewhere else.
when i take it off the ground everything is fine. on the ground, nothing...

please please please help here.. 2 videos...