It was just a line of FETs and a couple of resistors gone. I also changed the driver chip just incase.
Because both physical sides of drive worked fine on steer but not on throttle I took the mixing off the vantec and its perfect. Looks like its something in the programming for the mxing on the vantec? I can get round it by using the TX to mix, but I cant use the gyro then. any ideas on if it can be sorted?