A public service announcement from our technical department regarding the care & feeding of your burr grinder:
Never adjust the grind finer without turning the grinder on. The motor needs to be on & spinning as you adjust the burrs more closely together to ensure that beans are not compacted in the burr teeth, clogging the burrs or carrying grinds into the grinding chamber threads, thus jamming the burr carrier. This can damage and/or break the grinder and is not something that is covered under any manufacturer or retailer warranty.
So if you're going to tweak your grind to go a little finer, kick on the grinder first and, if you have beans in the hopper, make sure it's grinding normally as you move the burrs closer together. This will ensure that you don't clog/jam the burrs and potentially damage the grinder.