Don't do anything. Keep it exactly like it is. Recapping will increase the long term reliability, but it won't really better the sound quality. If the Sansui is functioning properly, no buzzes, static etc., then why spend money on it. Realistically, if the Sansui worked well for the past 38 years, then it probably will work well for another few years.
Btw, the 717 and the JBLs are a classic combo. Love the Stanton. Very cool.
Btw, the 717 and the JBLs are a classic combo. Love the Stanton. Very cool.