Knob is loose after light usage. - Primary Arms Classic Gen II Removable Microdot Red Dot Sight

Got this to pair with an attero arms rear sight mount for an AK that doesn't have a side optic mount. Was impressed with it at first considering the price. Seemed solid enough and the knob was very stiff and tactile at first, but after living on the rifle for a couple of months and seeing maybe 300 rounds the brightness knob came loose. Never dropped or abused it in any way that would cause it to break. It still works but I'm sure with another few hundred rounds (if that even) it'll loosen up even more and become totally worthless. I'm hoping primary arms has some sort of warranty so I'm not completely out of luck with it. Also, the dot isn't the most crisp, I've seen ebay optics with a better defined dot.