My M300+ used to make some really loud click-clack noises, especially when printing big parts or using a certain area of the build platform. The sound seemed to come from one, maybe two corners at the top.
The issue was the axes rods being slightly loose. You can test this easily, with the power off, just gently push or pull each rod longitudinally. If one of them moves, that’s your problem. Before tightening it, move your extruder head along the rod and get a feel for how smooth or stiff a working extruder should move. Again power must be off in order for the extruder to be moveable by hand. Now tighten the small grub screws on each end located on the underside of the “end mounts” where the rod terminates. Tighten gently until the rod can no longer move longitudinally. Move again the extruder head, making sure it moves just as easily as before. If you haven’t lubricated the rods in a while, do so now as touching them may have removed some lubrication. Now run the axis-check from the tools menu afterwards. If the test fails the first time, run it again.