Chroma errors in JVC S-VHS VCR

I would appreciate some insights from folks with VCR repair experience; I have a JVC HR-S7000U S-VHS machine with chroma problems and I do not yet have the service manual. I have downloaded a number of other JVC HR-Sxxxx S-VHS service manuals (from eserviceinfo.com) but these are for much newer machines and I doubt the chroma electronics is similar to mine; the only adjustments in these newer machines are gain related except for subcarrier oscillator frequency settings. There aren't any phase or linearity adjustments.

Please look at these photos of signals from my VCR:

1. This is a vectorscope display of the S-Video output of the VCR when playing full-height color bars from VHS tape (not recorded on this machine, but on another VCR and verified for purity and level)

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Note how the magenta and cyan bars are way off target.

1. These three images are of Patrick Stewart in "Encounter At Farpoint" from the Paramount tape; note the incorrect uniform color, the lavender tinges on his lips and poor flesh tones and white balance:

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Short of simply replacing entire subassemblies, what typically have any of you who repair and set up these machines done in the case of this sort of problem? Do any prosumer S-VHS machines have phase, gain and linearity adjustments in the chroma processor section? What about chroma noise?

I imagine that for VHS playback, the machine uses the "color-under" encoding system; have any of you effected component level repairs on earlier machines (with discrete oscillator, mixer, and modulator stages) to fix chroma problems and have notes involving bench instrument setups and measurements for alignment when the service manual is silent on these topics?

Thanks for any insights,

Michael