One of the absolute best tube tuner values on the market today is the
H.H. Scott 350-C. It is very comparable in performance to the 310-E, but is far more reliable. They turn up on ebay every so often, and typically sell for under $200. This is a far better tuner than the 350 or 350-B, or any Dynaco or Sherwood.
The 350-C tends to stay in alignment, and it is not picky about RF tubes or replacing of tubes.
If you purchase a 350-C, have your tech replace the output coupling capacitors
(two 0.1 uF 400V with Mylar film/foil), and the peak amplitude holding capacitor after the ratio detector (25 uF 25V electrolytic). Nothing else needs replacing, and these three parts will take a dull tuner and make it spectacular.
You will be hard pressed to find a nicer sounding tuner than the 350-C.
Cosmetic wise, it matches the later model Scotts, (233, 222-D, 299-D, LK-72-B, LK-48-B, 200, 200-B, LK-60, 260, LK-60-B, and 260-
-JD