Rob and Erik - The 400uF electrolytic is in series feed to the midrange. Bummer
Doh, then consider the Mundorf electrolytics:
https://www.partsconnexion.com/capacitors-ele-mundorf-e-cap-ac-series.html
or Axon film:
https://www.partsconnexion.com/axon-true-cap-film-capacitors.html
In either case, measure ESR of the original and be aware that reducing it significantly can result in more midrange output. :)
Best,
E

