Yamaha VL70-M Virtual Acoustic Tone Generator

Here we have a used Yamaha VL70-M. This is a tone generator, however, it does not work. We've tested this guy up and down, and we can not get it to do anything. This unit powers on and appears to work, but will not generate any tones. There's a very small chance we might have been using it incorrectly, but we did some pretty thorough troubleshooting with some reliable manuals.