If its on Fire !
In reality unless you experience a catastrophic visual or audible failure the nature of aging capacitors, in the main Electrolytic or say vintage paper in oils, means that drift from spec will tend to progress over time meaning that you may not really notice as you acclimatise to the sound over that period of time,,, A good multimeter is your friend...
@doogiehowser makes some good points
In reality unless you experience a catastrophic visual or audible failure the nature of aging capacitors, in the main Electrolytic or say vintage paper in oils, means that drift from spec will tend to progress over time meaning that you may not really notice as you acclimatise to the sound over that period of time,,, A good multimeter is your friend...
@doogiehowser makes some good points