My Gt-5 stopped working for some reason after 10 years of great performance. I decided to replace the internal battery and restore the factory settings following the owner's manual instructions. It started to work again, except for the expression pedal, wich now is working the wrong way. That means, I have volume with the pedal all the way down , and no sound with the pedal all the way up. Can anybody help me with this, please!??!