Put a nail in it.
I would say low mileage. Can't imagine this amplifier has a lot of key-down hours on it. Ed DuLaney got away with leaving off the individual bleeders because he was buying those caps in bulk lots. Parts from the same manufacturing batch tend to have well-matched characteristics. Individual bleeders have two functions. First, to bleed off the stored charge when powered down. The single bleeder across all three caps the factory used won't do this. Second function is to make sure the voltage is divided evenly three ways. Each electrolytic capacitor is also a resistor. A fairly high-value resistor, but all electrolytics have what's called "leakage" resistance. Three caps from the same day's production will tend to have nearly the same internal leakage resistance, and thus divide the DC voltage pretty equally. But if you don't have this advantage you can't count on getting a good match on this one of the capacitor's specs. Three caps each with a different brand probably won't match quite so well. The equalizing resistors serve to keep the DC voltage divided equally so none of the series caps gets more than the rated voltage across it. Bad juju when that happens.
