I think I need to fashion a similar tool.
I do weights 3 times a week at the gym, but had to give it everything I had yesterday to get the strut to lock-out.
It's never really been an issue before, so hope yesterday was a one-off.
I'm still experimenting with different ways of finishing the manual procedure - locking down the rear deck via the boot before bringing the rear screen down; and bringing the rear screen down and then locking the deck via the boot.
Maybe the stage at which I try to lock-out the strut has an effect on how difficult it is. I'll find this out after a few more goes.
Okay, pushing the strut back is much much easier if you lock the roof on the front headrail (top of windscreen) first.
Pushing the strut back should be the very last thing to be done.
So NOT as Alfa Workshop's otherwise excellent guide.