The drive train works great but near the end of the video the nut came loose and fell off the left return idler along with the wheel. Then the track on the right side came loose and the track started to roll off the sprocket. There was a second part of this video but it didn't save because the camera battery died. See more info and pictures at http://sites.google.com/site/qazwsx75... or at www.scaledtanks.com.