Originally posted by rfortson Sounds like it's time to return it for a new one. Where did you get it?
B&H. I went thru the dust alert, dust removal and sensor cleaning. Dust removal is a quick shuddering sound; that is not the knocking I see and hear. DR is settable for run at startup, but DA is not. You do it or you don't. That mechanism/logic should not occur in live preview!
Sensor cleaning also makes the knocking noise and involves locking up the mirror; live preview also locks up the mirror so I am thinking there is some relationship.