help on changing capacitors

Digi-key shows Jensen caps... Not sure that they will have this series, but any Excellent Film cap will work... A Copper foil,  A film and foil. Maybe a polystyrene.... These are inexpensive but still sound great with enough burn in time.  Ebay sells Russian polystyrenes in that size.  
In this case, it is the cap value that is more important than the voltage rating.  I normally like high voltage parts, but I can't see the circuit requiring 400 volt parts.  Good luck,  you'll find a good cap that will work fine.  Tim 

Those look to me to be alum foil paper in oil.... I believe the miflex referenced above would be slightly better Paper in oil. Jensen still makes a copper foil, but I’m not sure its available in 1mic and I don’t think that they are paper in oil.... Either way, in general, I would prefer the copper foils. A good polystyrene would be excellent, but most likely just a hint cooler or less warm than a paper in oil. They should however be slightly more defined  Good Luck

@ausaudio   Thanks for the info.  I probably have in 150 different caps in my shop right now.  My quotes as I thought that I eluded to are about the type of caps in general.  I have a few different PIO, they seem to share a rich tone quality, but not as detailed as some other caps that I prefer. My note about Digikey having Jensen was only because I looked. I had no idea that they were out of business. 
140208 Jensen Capacitors | Capacitors | DigiKey Marketplace