[Test-Equipment] Ballantine 324 True RMS meter.late model

[John]

I have a Ballantine Model 323 True Rms AC voltmeter to repair, the later 
model with the
solid state IC chopper S/N  025 8513
Can only find the early version with mechanical chopper on the net so far.
The two are completely different beasts circuit board wise.
Any one know where I can find the correct manual/circuit diagram for 
this later model?
Thanks John