Could you please explain how you did it?
War3 Model Editor has some bugs with saving and loading some parts of MDX files; ribbon emitters are often particularly troublesome. In this model two ribbon emitters have animated alpha, instead of having animated visibility like ribbons in most standard models.
The MDX file cannot be opened, as you probably noticed yourself, so you have to use
MDLX Converter to convert it into an MDL file; then you can edit the MDL file with War3 Model Editor (or Notepad).
There is a helper at the top of the node hierarchy which applies a scaling transformation to the entire model.
Scaling is animated in lines of code that look like this:
v - animation keyframe
x - scaling along the x axis (front/back)
y - scaling along the y axis (right/left)
z - scaling along the z axis (up/down)
Values larger than 1 increase the size of an object along the chosen axis/axes, while values smaller then 1 reduce it. You just have to change the values for x and y; don't change z unless you also want to change the flying height of the disc.
When you're done save the model and don't forget to convert it back to MDX before importing it into a map.