I recently added a Bartolini preamp to my Yamaha BB bass for more tonal variety. After a month I wasn't happy with the result. The +bass added more "boom" then bass and it felt like it removed the "thump" from my P pickup.. .clarity and J pickup sound was incredible. In the installation process I removed some wood but covered everything with shielding foil. Now with the factory pots and wiring.... the output is incredibly low, the 2 Vol pots only work in their upper 10% range, and the tone knob seems to do nothing. When certain parts of the pots touch the foil covered cavity, the signal dies... any ideas?