I made an interesting discovery about my Form2 when the mechanism that raises/lowers the platform started developing friction (losing lubrication?) and produced a slight groan each time it lowered back into the vat. The interesting part is that the orange cover for the whole machine is exactly the right size to resonate with this slight groan and amplify it into an EAR-SPLITTING groan. The sound is quite accurately described by the phrase in this thread’s title, which my wife coined from two rooms away WHILE vacuuming.
Fortunately a drop or two of machine oil on the worm screw just above the build platform makes it all go away, and serves as a reminder that there is no such thing as a maintenance-free machine. If it moves, it will need new lube sooner or later!