The millstones can touch if the mill is adjusted too fine. In our mills, the milling stones shouldn't touch each other while milling. In fact, the presence of the grist prevents such contact during milling because it acts as a buffer between the stones.
If you look at the milling chamber, you will see that the top stone that you removed is "sitting" on two small springs. So there is always an active "pressure relief" that protects the stones from damage by the other stone.
So you can set the mill in idle to the point at which the stones touch each other very easily. Then you should hear a slight "ticking". That's the sound of that "depressurization". The stones actually touch, then they "jump" away from each other. Again and again at tiny contact points. This is the best setting on your mill to mill the flour very finely. Don't let the ticking bother you! Do not let the Mockmill run idle longer than necessary. And never let the stones sharpen on each other in such a way that a loud "milling noise" can be heard.
Attention: The springs are loosely inserted. They can fall out if you turn the Mockmill “open” to remove the flour residue from the milling chamber.