Tants like that can be *much* longer lived, because the bead type is dry internally - no electrolyte to leak once formed. And since they usually have significant ESR in the first place - an ohm or two - they only got used where that aspect was negigible or useful in the first place (such as around 3pin voltage regs, or as coupling caps); so aging doesn't really make things go badly awry.
Replace them if you like but it's optional imo. And when tants fail, they usu. go with a very obvious pop
I think it unilkely you have a few unknown dead ones in there.
('Wet' tants are far bulkier and if they leaked, you'd know about it from pcb damage - they are in brass cases because the electrolyte is sulphuric acid... nice low esr while they last - which is decades - but expensive and frankly, do nothing a film cap cannot do better)
Replace them if you like but it's optional imo. And when tants fail, they usu. go with a very obvious pop

('Wet' tants are far bulkier and if they leaked, you'd know about it from pcb damage - they are in brass cases because the electrolyte is sulphuric acid... nice low esr while they last - which is decades - but expensive and frankly, do nothing a film cap cannot do better)