Keep it Simple,, just fix what is failing FIRST,,,, then move onto other things.

If you have the amp open and there are no obvious signs of corrosion or Leakey El caps then job is done.
Unless these things have sat for years in wet damp storage and full of roaches and rat poo then the rule is simple,, if it ain't broke don't fix it.
Yes visual inspection of solder joints is a good idea but don't replace parts unless they are causing failures.
No need to get too concerned about cap voltages as Most SS power supplies are likely much lower voltage that Valve amps. (if that is the worry)
If the amp runs on +40/-40 then the caps will be rated at 50VDC.
Some big SS power amps run on much higher DC rails and they can be dangerous.
ALWAYS pull Power Cord from wall when working on circuits,, don't just rely on the wall switch.
If you are concerned then just measure the caps with your meter to check they have bleed off the supply before working on the circuit.
The human body can handle up to around 80Volts but after that you have to be very aware of the danger.
Phil.