Help With Preamp Repair

I have an Apt/Hollman preamp I would like to get Repaired. Does anyone know who might be familiar with this unit, I have all the electrical schematics. The line stage seems to be fine but the phono section outputs are not balanced unless I switch the mode selector back and forth. I am looking for someone I can send the unit to to check it out and repair. Thanks- m-spadaro@ti.com