i sold my friend a guitar, an epiphone les paul 100.
before i sold it i replaced the bridge pickup with a bill lawrence xl500.
as of late my friend has been telling me that this guitar squeals and produces enormous amounts of feedback when used with gain but not being played.

can anyone tell me a possible reson for this problem, and follow it up with a solution?
thanks heaps.
I could be the jack or something, since your replaced the pickup yourself you should be able to check the wiring for bad connections.
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