Right, I've cribbed below pic from US Runners World website where same issue was discussed back in 2010 and no resolution found.
Star is location of the ache and the arrows indicate where it's tender / painful to touch:
I can ping about the place without issue; up / down stairs and then all of a sudden out of nowhere, sometime when static, the ache presents itself. I've stretched everything and foam rollered IT but the issue seems only to hide for a short while.
I want to avoid taking a hack saw to leg out of frustatioin. Any clues / leads most welcome!