VC500 - STD6 hotend - VZ carriage - MGN9 and Carbon.

Hi All! Trying to sort my newly built VC500 and have managed to get nice looking shaper graphs with an accelerometer mounted to the back of the carriage. However when I mount it to the nozzle I get a horrible x graph and my power spectral for x and y increase by more than double. There is no play in the hot end, but it does flex when I apply force to it. I think the increase in the power spectral density can be explained by the lever effect? but I cant work out where the other peaks on X are coming from? Anyone have any idea? FYI the graphs with N on them are the nozzle mounted results