My 3458A had just arrived back from Keysight after replacement of the A3 board and they didn't change the mains filter so I guess they don't see the newer filters as being problematic. Although, the level of support from Keysight has seemed to have gone down these days - they didn't bother changing the snap-hat batteries either even though they were well past due for replacement.
I will also check C15/C16 to see if those have been changed; I suspect not. If they are RIFA I will definitely change those.
