I've been using a setting of 12 for my Aeropress but thought I'd experiment and move it to 6. I can't move the adjustment ring below 8. The locking ring is loose, the handle turns freely and there's no grinding sound like rubbing burrs. When I first got it I could go down to zero, it was tight but the blue lines could be aligned.

I've looked around but can't find anything that addresses this. Do I need to take it apart and do the alignment thing? I've only had it for a month or so.

Check is there some dirt / old coffee dust in the thread

I sure don't see anything. I completely unscrewed the adjustment ring and pulled that plastic gasket down so I clearly see the threads and didn't see any obstruction. I also shot a strong blast of air but it's still stuck.

I sent an email to the OE folks so we'll see what they say.

OK, I gave it another clean with their provided brush and it's now working as it should. I guess it was something in the threads. I didn't see anything fall out but all is well. Thanks for the help.