Standard practice and common knowledge: amps of 20+ years need ALL electrolytic caps to be replaced or you have a serious risk of losing your speakers. Even in an unused phone stage as otherwise you'll see that if you omit those you will forget and one day you'll be trying out that recently obtained turntable and ...poof... Those old ROE caps often leak and that is not a shame after all those years.
Make a list of what caps you need. If the current ones with the same ratings are way smaller you may up the voltage rating. So an old 2200 µF 25V may be replaced by a 2200 µF 50V is that one fits on the board. In some cases it won't hurt to up the value itself but this depends on the function it has. The large filter caps for instance may be upped to have lower ripple but do make sure the diode bridge is rated for higher inrush currents (or replace those too for nice high current audiophile politburo approved diodes). For instance the 7000 µF filter caps may be 10.000 µF versions or even 15.000 µf if they fit physically.
You can use good industrial caps like Panasonic FC/FM or Silmic II if you want them to be "audio grade" and to have non ferro lead wires.
If you wait long enough till it breaks it will cost you some woofers, some power transistors AND the caps which is quite uneconomical. When you decide to make the wise choice, please clean the PCB where the old caps were to remove the acidic stuff that may damage the PCB. It likes to eat copper.
Freie Ton- und Bildwerkstatt: Mission Cyrus II Variante 3 - ca. 1989
Mission Cyrus Two