Brother VX 1125 only sewing in R position?

Hi

Any ideas what could be causing the machine to only sew when the needle is in the R position? In the centre and left positions no looping is occurring, and it sounds like the needle is catching on something (zig-zag stitching is broken too, only correctly looped on the R side). It's almost as if the whole bottom assembly has rotated somehow, but I cannot see a way to move it. Any thoughts would be welcomed.

Thanks