I've heard great things about Don. It does seem like it takes months for him to answer emails if at all. He is probably very busy and I know he teaches at a college.
Enthusiastic but Disinterested Recommendation
I just received back a classic AM/FM tuner from Don Scott (bdscott@nac.net.) He aligned it, tuned it, and tweaked it. He turned it into a supertuner from a DX and especially a sonic point of view. I will not say what tuner it is, because he works on several different ones. If you like, email me and I will send you a before and after of the specs. However, to say I am satisfied is an understatement and recommend his services.