I would recommend replacing the filter caps every 10-15 years to keep the sound buzz-free with no flatulence (ie weird noises on “big chords” or loud notes). Failing capacitors may start by just revealing a small bubble on the end, or others, like in the photo above explode dramatically and take a lot of other parts with them…some of those parts can be VERY expensive. Old caps look very cool, but they sound bad and can cause serious consequences.
This is one maintenance job that you need to leave to the experts. The filter capacitors can hold over 400 volts for a long time if they don’t have a drain resistor installed.