Former McIntosh repair tech, here.
Another clue; swollen tops of the electrolytics (can-type caps), and look for any dark liquid seepage from around the bases of the capacitors (some mfrs like NAD used a dark glue to help secure the cans, not McIntosh Labs).
All the internal PC boards WILL need solder joints retouched at their Molex connectors, and the carbon bias resistors (10, 12 or 15 ohms, depending on model, WILL have drifted if not replaced previously with metal film).
A properly biased McIntosh amp runs barely warmer than room temp even when driven moderately hard, so if the heatsinks are getting hot at all (or worse, one side heatsink warmer than the other), you need the bias circuitry resistors changed.
All the above will firm up the sound and re-focus the instruments better, as well as ensure future reliability and enjoyment.
Another clue; swollen tops of the electrolytics (can-type caps), and look for any dark liquid seepage from around the bases of the capacitors (some mfrs like NAD used a dark glue to help secure the cans, not McIntosh Labs).
All the internal PC boards WILL need solder joints retouched at their Molex connectors, and the carbon bias resistors (10, 12 or 15 ohms, depending on model, WILL have drifted if not replaced previously with metal film).
A properly biased McIntosh amp runs barely warmer than room temp even when driven moderately hard, so if the heatsinks are getting hot at all (or worse, one side heatsink warmer than the other), you need the bias circuitry resistors changed.
All the above will firm up the sound and re-focus the instruments better, as well as ensure future reliability and enjoyment.