I ordered this power supply...
I can confirm that it works.
The look isn't great, but I normally kept the brick on the floor anyway so I'd rather have the peace of mind than a pretty power supply...
View attachment 80354
EDIT: I should add that the color code for the cable coming from the old PSU to the G4 is:
+24V = Red
+24V = Orange
GND = Brown
GND = Black