I'd imagined that the fault was common across all failed units, as is often the way... but if not, this would make things a little more complex :-)
Unfortunately I don't have a repaired one to look at. But I know that the back gets cut out, a repair is done and the back is re-potted... There is no resultant bulge in the back, so nothing big is being added.
I'm almost tempted to send mine off to find out... but it's all black potting, so would need to x-ray it.
