A great example of this occurs in The Power of Un, which includes a machine called the "Unner" which Spoilers gets sent back in time in this same loop. /spoilers The odd thing is that it is this machine itself which controls time, and that rather causes problems, but in short the main character pieces it back together after it breaks, having received it in broken form anyways. The entropy argument always annoyed me here, as it is (implicitly) mentioned that he doesn't ever make a new one.