Driving straight

[Creator Mat]

Our team this year decided to go with a 6 wheel drive dropped center drive train (out of date but still similar pic here) it is based off of team 221's universal chassis. We finally got it driving but found that is biased towards one side and cannot drive straight. We couldn't find anything wrong right away before we had to leave.

So long story short does anyone now of any common reasons for this type of drive train to be driving in circles?

We know it isn't a programming error (first place we checked) and plan to do a speed test and to check the alignment tomorrow to see if our frame is crooked. Any other suggestions? Other than driving in circles it runs fine.