If you find a problem during your viva prep, big or small, do you need to solve it immediately?
A typo might just need a note making for later correction.
A clunky sentence could need underlining to revise, so long as it is clear enough.
An old idea could be left alone.
Not everything needs to be addressed when you find it. Maybe some things never need resolving. If you find a problem on the way to getting ready for your viva, ask yourself if you can park it: can you put it to one side and leave it for another time?
It may be that you can’t! But perhaps you can focus first on the bigger work of getting ready rather than every little (or big) issue that you find as you prepare for your viva.