On Wed, 20 Nov 2013 07:47:41 -0700, Bob F wrote:

...snip...
I might be a good idea to test for continuity to ground at the unknown
end
before some of the suggested tests to find out it somethink is connected
to it.



some usually gets through even if 'grounded'

However, better if possible to inductively couple to the shield, less load
for your source. Or, just tap into the shield about a foot away from the
grounding.