Very nice instrument, and good repair.
The 343A is more stable and accurate, than the 341A, and it has 7 digits resolution, instead of 6.
The 343A also has linearity alignment of both decks A and B, whereas the 341A only allows for alignment of deck A.
Better to replace all these old electrolytics, that might improve noise performance, also.
Some plastics become very brittle after 40 years, so pay attention on the replacement of these spacers.
Would you mind determining the Reference Amplifier type inside your unit, please?
That's Q14, under the black hood, should be near that faulty electrolytic.
Is it already an SZA263, or still the older T.I. DH80417A (or similar designation)?
Thanks.
Frank