Tom gives a good run down on B+. One of the terms you will CONSTANTLY see
used here. If you look at any little radio the battery is the B+ source.
On your set odds are the heater is NOT the problem. If the G-2 is
set right look at this:
The pix is bad when the set is cold but gets better with time.
The pix improves with reduced brightness & contrast.
Thats all assuming the 200 V DC for the three video outputs is good.
At this point a manual would be needed. Any NAP chassis will work if
a close match ( C-5, C-6 etc. ).
73 Zeno
LFOD !