Reply to Question about a Knob in S4

One of my knobs in S4 is a bit more heavy to move, and when i take it back to kill a bit the bass, you feel its like touching inside with the case or sumit that makes it a bit harder to move, only happens in like 5% of taking it back, but i wonder if i can do something to make it move like the others. Doesnt really bother me but could just have been some other knob of non main decks