How to dismantle Campag Ergolevers (hex key won't turn)
From my experience (see below) since asking the questions, the answers are:


Am I doing something wrong? NO
Is there a known problem with these sometimes seizing? YES - known now by me!
If so, any ideas about freeing the seized part? YES thanks @ojs for the suggestion.


My experience was that I broke the plastic body of the lever. This was because it was held in a vice and I was putting a great deal of torque (lefty-loosey, thanks @haniel-r-hicks :-) ) through the seized bolt in a last ditch attempt dismantle it.