FAQ X108G Microphone buttons (1 Viewer)

[Krazypcs]

I recently purchased a secondhand X108G (outdoor version). On playing around with the microphone controls, i have noticed that i have a small issue with the up and down buttons. If i press the up button, it will tune my frequency up (which is correct) but if i press the down button, it still tunes my frequency up and NOT down as it should.
Has anyone had the same issue or am i missing something.