So ….
BEFORE
AFTER
So - basically, no difference! 
Well, there is a difference that’s not visible in the photos … it now doesn’t frigging work.
Constant Gimbal Overload messages.
Stripped back down a couple of times and confirmed all connectors are good. No change.
Sounded like the camera was slightly catching the anti-fall hook at the back, so stripped down again to try without that fitted. No change.
(Yes - I know the top of the body isn’t fully on … taking that on and off is the trickiest part of the palaver … so powered up before fitting it on to check gimbal.)
Now what …. ?? 