Hi Lee, I am interested in having my NAD 3140 and 2140 amplifiers refurbished/upgraded. Trying to find someone online, I keep coming up with your name. They both work, haven't had a major issue yet, but are nearly 40 years old, and am told they can actually be made to sound better than original. Better to do before there is a serious failure. Would that be something you could do or refer someone else? Thank you.