Two important errors in MMX
In the longitudinal arm:
The assumption that transverse forces propagate as c+/-v should be followed by the same assumption regarding longitudinal forces. Therefore, the assumed effect is compensated and not observable.
In the transverse arm:
The assumption that the vector sum c+v is reflected by the distant mirror is wrong, since the mirror is transparent to v. Therefore, only c is reflected and constant in equipment frame, and therefore no effect in the transverse arm in MMX.
See more in the PDF Errors in Physics