Zap Machine Making buzz sound

[TonyDaou]

Hi:
Since i bought my zap machine a buzz sound always is running when its on the green light and when i switch to the red channel it gets louder
i live in beirut lebanon someone told me that this problem is cause in our area we don't have the middle ground jack
please let me know what i can do to fix it
note: i tried many 9v adapter and all gave the same result

[acaciaflora]

did you try a battery? if so, what did you see?