You are probably talking about the door latch rattle. To see if that is the issue, place a few turns of electrical tape around the metal loop on the door jam where the latch comes into contact with it. If the problem goes away, just leave the tape there. Replace when necessary. Or to make a more permanent fix you could take and coat the thing with 5 minute epoxy. 5 minute epoxy has the same consistency as electrical tape but will bond more permanently especially if you totally encase the metal 360 degrees. If you make a mistake with the epoxy, it is soft enough that it can be removed with a box cutter and then you can try again.
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