They’re not electrolytic capacitors. Because it’s a balanced circuit the output is through two output capacitors. So there are two 1uF 400V Jensen’s on the positive/negative output. (These caps appear to have a history of failure in these amps.)
The Miflex can be got here: MIFLEX KFPM-01 Capacitor, 1.0uF 600Vdc, Copper Foil Polypropylene Film (partsconnexion.com)
Info on the caps: http://www.miflex.com.pl/assets/dokumenty/KFPM-01-ENG.pdf (partsconnexion.com)
The Miflex can be got here: MIFLEX KFPM-01 Capacitor, 1.0uF 600Vdc, Copper Foil Polypropylene Film (partsconnexion.com)
Info on the caps: http://www.miflex.com.pl/assets/dokumenty/KFPM-01-ENG.pdf (partsconnexion.com)