Internally- Apart from any repairs, the unit has been disassembled, cleaned, & hardware tightened, all trimmers, switches, edge connectors (re-soldered), and jacks chemically cleaned, all of the potentiometers on the face panel have been replaced with new ones, all trim pots replaced on the oscillator board (multi-turn), new .01% matched resistors, tuning transistors & capacitors on the oscillator board, new overload lamp, new cinch connectors on the pitch/mod box & keyboard, the power supply has been rebuilt (all capacitors replaced), new power cord & clamp, new heat sink compound for the power supply & oscillators, the keyboard completely rebuilt (circuit board standoffs replaced, bushings replaced, key contacts & buss-bars polished, key action refurbished & spaced, and keys cleaned & polished), new fuses, and it's been completely calibrated (power supply, A440 tuner, oscillator tune, tracking, scale, octave.) This will likely be updated as so much was done to this one.