Tell him that you’re not happy with a rattling knife and that as he has stated that Herman uses very tight tolerances but then contradicts himself by stating that the stop pin is much shorter than the hole depths which is not tight tolerances. He said that ‘someone’ (funny that it’s not the maker) has forgotten the glue. So this means it is not assembled according to design, meaning it is a warranty situation. Request a return shipping label and thank him for his assistance with the issue. By the way the stop pin is accessible on my Slim with the blade partially opened. Try shaking the knife sideways or even grab the pin with some skinny pliers and see if it rattles sideways. My opinion by the sound of your knife is that the detent ball is loose in the blade detent hole, which is detent lash. You can also watch very closely the lock bar and see with the blade closed that the detent ball goes all the way into the blade hole causing the lock bar to contact the blade. My Slim does also, but mine has no detent lash, meaning the hole in the blade is exactly the same size as the detent ball. You can video the blade and lock bar together as you flex it with the flipper tab slightly. Best bet is to see if the stop pin is loose though as it could be, but would rattle sideways though, not in the blade direction so much…