Ever had a guitar that is just wonderful apart from when you turn the gain or volume up loud and suddenly it emits a high pitch squeal that even has the neighbour's pet dog running for cover??
This is what is known as microphonic feedback- and the most likely culprit is the pickups' coil windings being microphonic (in some cases you can talk into the pickup and hear it through the amplifier- just like a mike).
Expensive pickups are usually well and truly wax dipped (potted) and as such are not so prone to this problem, but many pickups are not and the resultant feedback is just horrible.
Some older pickups that may have been wax dipped may exhibit feedback as the wax has dried out and no longer holds the coil windings firmly in position.
But help is at hand!!
We have a wax dipping facility here that can eliminate most cases of micro phonics in a pickup.
So whilst we are more than happy to offer one of the fine replacement pickups that we stock(Remember that we keep ASL, Bare Knuckle pickups, Seymour Duncan, EMG, Dimarzio and TV Jones), we are now happy to offer wax dipping to rectify the problem that may be spoiling an otherwise fine sounding pick-up.