The correct gearknob for a Series MM looks like this<br> http://mmoc.org.uk/mbimage.php?src=1254683446_10546 <br><br> http://mmoc.org.uk/mbimage.php?src=1254683467_10546 <br> I have pictured it alongside a horn push as a reference was made to it being the same size, which as you can see, it is not.