hi! i noticed that in my new (but used) Lakland 4-94 the volume knob makes noise when turning it. the problem is that im uising a looper to play solo live, and i cant afford those noises getting in the looper. and i use a lot the vol knob. is there a way of "cleaning" the knob? or i need to replace it? i have a gig on the 20th so i have to fix the problem before. i was thinking of borrowing a volumen pedal if i dont have the problem fixed..... so what can i do to solve it? thancks!