I have a cheapo Epiphone SG Special I picked up for free from a neighbor. Grungy; bolt on neck; big crack in the lower bout into the control cavity...generally used and abused. When I got it I took it all apart and cleaned everything up, restrung, adjusted action...and voile!, it plays and sounds great!......except the pickups don't clean up much with the volume knob. So I'm wondering if how a pickup cleans up is more a function of the pickup or the pot. Can anyone enlighten me? Thanks in advance for any info.