Back to the TV, I just worked through the preliminary purity & convergence adjustments, and saw plenty of R-G-B in the raster, dot, and crosshatch test patterns. No surprises. Then I switched to a color bar pattern and saw . . . shades of gray.
Same monochrome result if I play a DVD or receive a broadcast on rabbit ears from the in-house modulator. I adjusted obvious things like the color control, color killer & noise inverter, AGC, and so on. I also tested the obvious tubes, which are all fine.
When I use the fine tuner, it's as if the tuner is not centered on the frequency. Turning fully counterclockwise, you eventually lose the signal, as you'd expect. Midway in the fine-tuning range, picture is fine (although monochrome) and audio is absent. Cranked all the way clockwise, you can just begin to receive audio, the picture is still fine, and there's still a monochrome picture.
It feels like the frequency center -- where color and audio pop in -- is just beyond that far range of the fine tuner. This is the same on every channel.
I'm used to tuners where you remove the knobs and adjust an individual oscillator slug (for the selected channel) through a little hole. This tuner appears to be built that way, but I'll be darned if I can find the magic hole. The manuals that I have don't mention the oscillator slugs except in the context of a full-bore tuner alignment, which I'm not equipped to do.
If I'm missing something obvious, or barking up the wrong tree, please tell me now
Phil Nelson