[exray]

It could be that the rectifier was replaced with modern diodes underneath the chassis. Unless other measures are taken sometimes that leads to higher voltages and may be related to overheating. But if you're referring to the audio output tube it runs quite hot in normal operation.
BTW, "leaky" caps refer to internal leakage not necessarily visible from the outside. If they are the original paper caps they probably are leaky and should be replaced if you're going to use the radio often.