My policy now is:
If it is not yet-broken, do not (dare-touch) fix-it!
Being quite handy; many-many times, seeing some 'things' that can be improved, I did take the plunge ... then ...
Meet them (mischief) rusted broken-screws, hard-to-find parts, product id, manuals, you name it /etc.,
(good luck finding vintage parts).
It is like opening a can of squirming worms; unforeseen headaches/mischief/challenges seem to crawl from practically everywhere.
In the end, after some unexpected extra $$'s, the problem does get fixed.