Why does Jennings repair the future-viewing machine?

Jennings offered some insight as to what his motivation was for using the machine again, when he spoke the following words while starting it up:

"Alright, let's put this thing to good use one last time... to get us outta here."

He apparently wasn't sure how he and Rachel were going to get out of there safely, after destroying the machine. This is more or less confirmed when Rachel subsequently asks him how they're going to get out of there, and he responds:

"I don't know."

You noted that, up to that point, he'd been relying on the items his past self had provided him with, as if to question his decision not to continue relying on those alone. There are a couple of things to consider here though.

Firstly, up to that point, he had nothing better than those items to work with. Upon regaining access to the machine though, it makes sense that he'd view that as a preferable option to betting everything on blind faith that he was already on course for a happy ending. He had good reason to doubt that he was necessarily on course for a happy ending, given the recurring dreams/visions he'd experienced of being shot and falling to his apparent death from a catwalk.

Secondly, after using the crossword puzzle to debug the machine, he only had one item left -- a single bullet -- and he clearly couldn't see how that was going to get him and Rachel safely out there. He may've reasoned that his past self had intended for him to use the machine to facilitate his escape. Either way -- whether he thought he was acting in accordance with whatever plans his past self had made, or forging a new path of his own -- he had understandable reasons for doing what he did.

As it turned out, it appears he was 'supposed' to use the machine again, since the alarm on his wristwatch subsequently went off at just the right time for him to dodge the bullet that would apparently have killed him, causing the bullet to kill Rethrick instead. Either that was one hell of a coincidence, or his past self had accounted for everything that occurred up to that point, including his final use of the machine.

The only thing I can't work out is why the machine showed him getting shot when he used it that final time. Perhaps that was his future at an earlier point in the story, but after his past self provided that watch for him -- with the alarm set to go off when it did -- that future should've been averted, and he ought to've seen something different when he used the machine again. I could post this as a separate question, but I suspect it's more of a plot hole than anything else.