I have rebuilt 3 McIntosh amps myself that were a minimum of 42 years old each. One of the amps really needed the overhaul but the other two were pretty good still with all their voltages and biases just right. Of course, with age, capacitors loose their dynamic capability even when statically they are still good so you would probably benefit from the rebuilding but it isn't in dire need just yet.
So far in my experience, changing out the diodes/rectifiers makes an even bigger difference than new caps when you check the waveforms on an oscilloscope. I suggest HEXFREDs and not NOS parts as technology has advanced greatly in diode design in the last 30 years.
So far in my experience, changing out the diodes/rectifiers makes an even bigger difference than new caps when you check the waveforms on an oscilloscope. I suggest HEXFREDs and not NOS parts as technology has advanced greatly in diode design in the last 30 years.