Is there any resistance in the pedal, compared to the other side.., like feeling pressure?? I've attached an exploded view of the braking system on a 574. Note this is with SN 7365 and below. The only difference I could see with models after this SN is there is no orifice and screen ( Part #31 & #32 ) on the later models.
Could be the master cylinder (#5) is bad..? Or posibly something in the screen and orifice blocking the oil flow..??
Take note, there is a master cylinder for each side.