Chroma/Luma (or s-video) Problems on 128DCR

All,

I've asked a number of places, but I thought that I would get the thoughts
of the fine folks, here, as well.

I have a C128DCR NTSC that has issues with signal level on chroma, from the
video connector.  Signal levels seem to be just fine at the RF connector,
and the picture is fine, from that connector.  From the video connector, to
a modern TV or monitor, the picture is excellent quality, but monochrome.
Checking the output pins on the video connector, the level is very low, on
the chroma signal.

I have changed:
1) VIC-II (8564)
2) Clock generator (8701)
3) Crystal (NTSC/14 MHz)
4) RF modulator

All to no avail.  I'm scratching my head trying to determine what else
could be awry.  I looked at the traces on the board, and I see no damage,
between the RF modulator and the video connector.

Any other suggestions would be most welcome.

Thanks!
- Alex