That ballast tube can cause problems, as the resistance elements can break off from their connectors in the base of the tube where they connect with the pins. This can happen even in NOS tubes, so your best bet would be to replace it with seperate high-wattage resistors. I had a set link this, and really learned to hate that ballast tube. It Is normal for it to get hot during operation, and it will make some funny noises and smell funny when the set if first heating up. The ballast serves as a dropping resistor for the tubes in the set, as I recall there are two seperate fillament strings in the set, each adding up to less than 115V, so a dropping resistor int he ballast is needed for both of them.
You can read more about replacing the ballast with resistors here:
http://www.antiqueradio.org/motvt73.htm
I have some information about the exact connections and values of the resistors in the ballast I can find if you are interested.
Good Luck!