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 

Check HiFi Collective, UK based, they seem to have some stock of Jensen.

G

Michael Percy is the go-to guy for capacitors. His website isn’t slick. But, he supplies the best engineers in high-end audio. https://www.percyaudio.com/

Right. Caps are easily swapped. Think of it not as a repair but as an upgrade. Shop for your caps the same way you would shop for any other component- by listener impressions. If you want a silkier more liquid sound, buy those caps and that is what you will have. Do this and you needn't worry about maybe making it sound worse. Almost certainly the caps used were so cheap anything will sound better. Only question, by how much. Oh, and use a solder sucker to get that old solder out of there and use Cardas Quad Eutetic.