Help with crossover capacitors

Hi @dannybad ,
You can try to bypass compression driver filter capacitor with Duelund Cu-Sn 0.01uF bypass capacitor.
I did it in my Altec 604E with vintage oil 4uF capacitor and with Duelund RS main 3.9uF capacitors. I like results in both cases.
Even in parallel with already very good Duelund RS capacitor, bypass capacitor my speakers sounded more vivid, organic, with better tone. Only drawback was it made sound a little bit less focused.
In case of  vintage oil capacitor the difference cause by  Duelund Cu-Sn 0.01uF bypass was even more positive.
Regards,
Alex.

It just possible option.
On the first stage to update the crossover with not expensive and good sounding capacitors.
And if you like result go to the next step of upgrade.
There are a number of options there including use good bypass capacitors.