Both of the manuals I have use the same circuit diagram, which shows an obsolete current source design and 2500 ohm cathode resistor. In the manual marked "Second version with corrections" the parts list and instructions show a 3K resistor, but the circuit was not updated. It also shows a 100K resistor across the input jack, but the text and the parts list show 249K. There may be other inaccuracies - these are just the errors I noticed yesterday and today. As far as I know, there was never a more up-to-date accurate schematic.