What do you do when you get stuck in production?

Ive got this tune Im working got to the middle have an idea whats going on after this bit (that I cant get) but Its a crucial bit I feel and nothings happening up top, no matter what I try it just doesnt fit?

I do have a couple of ideas for other tunes but Id feel guilty leaving this tune as it porbs wont be finished :cry: :lol: .

What do you do when you get stuck producing?