At times when a pickup is epoxied it is difficult for the hot wax to penetrate the voids in a pickup. At times the wax will help solidify any movement in components that could vibrate and help eliminate the majority of the feedback. Playing at high volumes and especially using overdrives will cause all kinds of feedback within the instrument and other hardware besides the pickups.

Any ferrous component in the pickups such as loose pole pieces, springs, height adjust screws, guitar strings used as ground straps within the instrument can cause interference with the pickups and even feedback as well as acoustic feedback common on hollowbody instruments and ones with hollow cavities.