I have an AXA tool post with the parting tool holder (cdcotools.com part no 12004 sorry the link wouldn't cut and paste for me).
I use his blades too- or at least the ones he supplied a couple of years ago.
The blade has an angled top surface as well as side clearance and is jolly hard to set in the holder – which has a vertical side face. The blade wants to tilt over so that the side clearance on the tailstock side is obliterated.
I currently use a little bitty bit of wire next to the blade to hold it vertical (ie equal side clearance) but it is a nasty fiddle.
I know that I'm not robinson crusoe – what is the best solution?