True, but there's not much to the early models really. Maybe just a couple of capacitors to replace and controls to clean.
Here's the pinput for a 12LP4:
http://www.bunkerofdoom.com/tubes/sy...crts/12LP4.jpg
The filament is between pins 1 and 12. That's either side of the key on the base. Check for continuity between those pins. It should be a very low resistance.
P.S.
I'll haul my Motorola chassis out in a few days and we can compare notes.