Just try some new tubes before doing anything else. High quality vintage gear is good stuff and can have many more years of service. The things to watch out for are corrosion and dried out electrolytic capacitors. I think it can be particularly rewarding updating vintage gear with modern high quality components. I bought my ARC SP-6b preamp in 1989. A few months later I had it modified by a buddy who was skilled in audio, a hobbyist and in the business of upgrading gear. Circuits weren't changed, just upgraded internal wiring with Litz, gold plated RCA jacks with teflon dielectrics, Wonder Caps and wire wound resistors in place of the carbon filled ones. My buddy also added better quality trim pots in the bias circuits. These were many of the things ARC incorporated into their later models. I used that preamp for the next 14 years. It sounded great. I only changed models eventually, because I wanted to get into the low output MC cartridges. I discovered NOS tubes too late in life. I'd love to go back and hear my old SP-6b again with NOS tubes.
