Just bought a new Ibanez SR755. I've noticed that there is a loud hum when plugged in. The hum continues when the battery is removed (but no string sound). The hum is loudest when the volume knob is half-way. With the volume knob all the way up or down, the hum is *almost* gone. If I touch the strings, the bridge, or the cable (to the amp) the hum decreases. I opened the control cavity and looked around, but didn't see any loose ground joints. My volt meter shows 0 ohms from the bridge ground to the output jack & volume knob pot case. I tried my old bass and no hum, so it's not the cable or the amp. I assume from my search that I have a bad ground. Any ideas on where to start looking?