Looking at the schematic, I can see that with some meters, if the resistances are measured with the right polarity, there can be some current flowing through the C4S output transistor back to ground through the C4S bias resistor (120K or 220K) which would produce the results in the manual. With the meter leads in the other polarity, I would expect your measurements - these would seem to be the more appropriate ones, and the manual should probably be corrected.
If OB is not more than 100v, then 158 on OA is fine.