Maybe new Tubes and a good Cleaning? Have the Jacks all cleaned with Electronic Parts Cleaner.
Try also just replacing the first Preamp Tube. Sometimes they can OD whole Amp too much, when they're going out.
But if your Tubes are all old, that and a good "Tune Up" at a Tech's would probably be what is the best bet.
Early 80's 1957 U.S. Vintage Reissue Stratocaster (Surf Green)-Warmouth Soloist Pearly Gates Neck, Pearly Gates Bridge- Larrivee D-03 (Mahogany/ Spruce)
Carmen Ghia Head- Marshall 112 Cab W/G12H 30 or Custom 4 X 6v6 Head or Budda Twinmaster Plus Head-Traynor 212 Cab w/Eminence Texas Heats.
Mo'D-Eternity-Blues Pro- Timmy-BYOC Chorus/Vibrato- TC SCF- Korg DT 10 Pedal Tuner