Sorry guys – I had glugged a couple of glasses of Monkey Shoulder last night and it had made me a little giggly 😀

I believe that the mod to the B Angels a/c that DF referred to is actually just a spring fitted to the control system – not so much to give it a nose heavy bias but to take out backlash/play in the system to make the flying controls feel taut/less sloppy !
A similar but smaller spring was sometimes used on potentiometers in flight test instrumentation – the spring tension held the backlash/play onto one side of the lever/or attachment which meant that all readings/indications were consistent and therefore it reduced hysteresis in the system recording/readings.

Just to finish about F18 tailplane trim – as far as I am aware it has 2 basic modes…
Fully auto with gear up
Manual with gear down

There may also be a standby trim system but not sure !

rgds baz