Is the coil getting power (usually, but not always less than battery voltage)? Is the coil being triggered? You gave no year and I'm not familar with MB, so I don't know if this is mechanical or electronic, but basics are basics, you have to supply voltage to the coil, a (ground) return path in order for current to flow and build up a magnetic field, then you must interrupt the primary current to trigger the field collaspe that creates the spark. If any of these are missing, all the coils in the world won't work.
inter change the coil so that you can identify the condition of the coil . iF it still does not work than the coil is good.The problem could be from the control module primary current to the coil that is not firing.
