I've now replaced all the caps and it's on soak test - seems to be working
fine (this post hereby constitutes my 'tempting fate' test). There wasn't
anything obviously wrong with any of them - I ought to make myself an ESR
meter sometime to test this sort of thing.


There usually isn't anything obviously wrong, they have to get REALLY bad
before they leak or bulge and most circuits will stop working long before
then. An ESR meter is second only to a DMM for repairing modern stuff.