I remember back when, that when I was rebuilding that circuit I would also replace d302, and c305 but I would increase the value of r303 slightly, ( got to find my notes, it's been a long time ) so that the voltage delivered to IC601 would be lowered from 30v to around 26v. That would still allow proper operation, but ran a heck of a lot cooler. This was done as per conversations with the tech guys from WG.