I am afraid I am an inveterate fiddler.
Had a long (10 minute) flight with the trainer this morning in probably the calmest weather it has seen so far.
It was ok but I felt it would be a bit better with the CofG a bit further forward.
How to do this rather than simply add lead?
The battery is already right in the nose and the ESC is along side it so the only other thing was to move the motor forward.
To give clearance for the prop the wing tailing edge now has a cut out.
A second flight this evening confirmed the improvement, nothing dramatic, but it is a bit more docile.
A final adjustment will be required when its new slightly lighter battery arrives.
I could not video it as the LiPo in my Key Fob cam has expired.

I have a replacement battery on order but soldering it in is apparently a bit fiddly.