Guitar pickups? Plz help!?

I have a 2008 gibson sg, whenever i switch from treble to rhythm, the neck pickup barely works...i had the inside of the guitar cleaned and it still cuts out. I have to keep playing with the switch until it finally sounds like it kicks in and works but it sometimes crackles out and no sound or crackling comes from my guitar when on rhythm. What should i do? And what is it? Please help!