I have a Yamaha RBX200 that a friend gave me, he said if I can fix it, I can have it. I replaced the output jack and the volume and tone pots. I compared the wiring to my friends that is the exact same make and model and all looks fine...however...when I plug it in there is no sound except for a hum...if I touch anything metel, the hum stops so I am assuming it is a short in the ground somewhere but I have no idea where...if I touch the pickups while touching metal you can hear the scratching sound of me rubbing my finger on it...if I touch the pickups without touching metal the hum gets a lot worse...any ideas on how to fix it? Are my pickups bad? Please help!