Although my tube tester experience is limited to the excellent Hickok 800A I mentioned above, as someone who has worked extensively with both vintage hifi equipment (1950's and 1960's) and antique radios (1920's through 1940's), I would expect that a considerable number of the non-working testers that are out there would require only routine simple things to be restored to reasonably useable condition.
Namely, testing or substituting for their own internal tubes (my 800A uses two readily available rectifier tubes), spraying contact cleaner into switches and contacts, and perhaps replacing an electrolytic capacitor or two.
Also, a way of finding tube testers in good or at least known condition might be from antique radio collectors. Many of them seem to be getting older and selling their collections and equipment. You might try subscribing to Antique Radio Classified (you can request a free sample copy), and then watching the classifieds in it and/or placing a want ad. And also perhaps following the various antique radio-related forums which are out there on the net.
Regards,
-- Al
Namely, testing or substituting for their own internal tubes (my 800A uses two readily available rectifier tubes), spraying contact cleaner into switches and contacts, and perhaps replacing an electrolytic capacitor or two.
Also, a way of finding tube testers in good or at least known condition might be from antique radio collectors. Many of them seem to be getting older and selling their collections and equipment. You might try subscribing to Antique Radio Classified (you can request a free sample copy), and then watching the classifieds in it and/or placing a want ad. And also perhaps following the various antique radio-related forums which are out there on the net.
Regards,
-- Al