my question is how can i check the 115.41 ballast in this radio.also is there a sub for 25z5

:my question is how can i check the 115.41 ballast in this radio.also is there a sub for 25z5
:
The resistance measurements for the ballast are shown on the bottom right hand of the schematic:
http://www.nostalgiaair.org/PagesByModel/472/M0005472.pdf
I don't believe there is a direct replacement for the 25Z5.
Carl T