Ok... an update.

I decided the solder joints probably didn't take due to me not cleaning the pads after desoldering, and hence them possibly having electrolyte still on them.

This was borne out when i desoldered all the replaced caps and found many sticky points, so I'm now going to wash those areas.

In the process of desoldering, I accidentally ripped out the positive pad on capacitor C8 (10µF, 16V) - I'm sure I don't need to explain why I feel really bad about that.

Can anyone here tell me where it connects? Or, advise me of a way to safely get the trace reconnected to the cap?