I gave up hand cranking that bad boy a long long time ago. I do try to use as low of a RPM as possible.
You'd think one would hear it if it was binding or the rollers were striking the hopper. Suspicion is that you got a bad mill. Unfortunately.
The BC comes completely apart. Easily. Too late now (if you have sent it) but the mill disassembled might have revealed whether the rollers were rubbing the frame or given some other indication.