I sent my V70 amp to Audio Research some years ago. The amp was almost 20 years old at the time. They did a superb job on it and the inside looked like new. I think they actually cleaned the circuit board. I would not be surprised if they do the same type of thing to your preamp. They want to clean every thing thoroughly and check every connection so it sounds it's best. Let us know what happens when you get it back.
