Sorry I have no idea what the Miniature Modulator is. Can you describe it better?
I am assuming the OP means the Thumbnail size slider but in my import window there is no way to turn it off/on except change to the quick import mode.
Sorry I am German ;-)
Yes it is the Thumbnail size Slider which changes the size of the small pre-view pictures...
My IMPORT screen always show the Thumbnail Slider but I can turn it off/on in the Library module using the T key. You may also have it unselected. Click the little downarrow at the right hand end of the toolbar next to where it says SYNC/AUTOSYNC and this dropdown will appear and checkmark "Thumbnail Size"
Thanks to all for the comments and recommendations.
It seems that there is a bug in my system. I see the thumbnail size slider in the dropdown menu as well and it is selected (Library module).
But it appears not on the import module.
Post a FULL SCREEN clip of you import dialog