When I get stuck, I destroy my creations.
When you're seriously stuck editing something complex... save a back-up of the project.
Then magnify the problem area.
Wholesale delete the problem.
Start with a blank slate.
Now try again.
Think of an entirely new direction for the scene / sequence / act.
Few things get the juices flowing like a blank page.
It's a bit more work building a new toy than it is to smash the square through the circle, but in the end you get a better result.
And it works.