Tommy Del Leerious

Im fixing my friends CT701 for his birthday and I had the same problem with the melody setting. I followed @Chas ' Instructions as far as turning off the accomp and playing with the balance. I can hear the keys if I have it plugged into my amp and turned up all the way but it is still very soft. whenever I play one of the keys on the melody side of the keyboard they send this clicking sound to my amp. If someone on here could take me through the trouble-shooting I would appreciate it.