Change kernel cm12.1

I was wondering if anybody knows how to replace a kernel from a build of cm12.1 to another build, im asking this cause latest build of cm12.1 by the marionette the kernel works great on my device no random reboots really fast, but the only problem is that camera is not working, so i wanna try previous build with the latest kernel, since i tried that build and the camera was working but i got random reboots. hope you guys can help me out

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