RGD R135 3 band radio

[Crackle]

So why is there a VDR in the circuit, what is it doing, how can I test it to check its working???
Also there are not many voltages marked on the schematic but the ones there, do they look about right. I am getting nothing like the ones given.
For instance;
T301 E 3.8v, B 3.1v C 0v
T302 E 3.7v, B 3v, C 0v
T303 E 3.7v, B 3.1v, C .5v
T304 E 0v, B 2.9v C2.5v
T305 E 2.4v, B2.9v, C 0v
For the above voltage readings I am measuring with the negative probe on point A which is the neg supply rail for the RF section, see schematic in post 1
I think I am going to have to dismantle an ITT Colt and do direct voltage comparisons between a working Colt and this R135.

thanks
Mike