I was checking component values and noticed that R64 is a 10K pot instead of the marked 1K on the schematic.? Also, R69 is totally missing.? Apparently this unit is really early (s/n 00134 of the 1212A sequence) and later units have the 3480¦¸ resistor and a 1K pot.? Actual measured resistance is in the mid 3K range so that's believable.? Even the backdating info in my copies of the manual doesn't cover this very early rev.?
