I've got a Mexican strat that produces a quiet buzz when any of the three single pickups are selected. If a combo of Pickups are selected, the sound is clean.

Any suggestions as to what's causing the noise or how I can fix this?
Thats a strat for you. Single coils hum, thats just the nature of them. But when 2 are on at a time they cancel eachother out. That's why the humbucker was made.
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