Well... I got mine brand new for Christmas. I noticed that there was an O-ring installed on the drive roller to friction drive the slave roller. I thought that was weird. I checked the gap and went to crush the first batch and and the grain would not feed into the rollers. I looked and saw the o-ring was gone.
I completely disassembled it to to install a new o-ring, and discovered the two frame halves are only aligned with each other by the little sheet metal screws (going through aluminum sheet metal), and the two through-bolts that hold it to wood base. When tightening those two bolts, it's easy to twist the two frames out of alignment causing the non-roller bearings to bind.
Got it all together and got about two cups crushed before the same thing happened.
This time I put two o-rings on, and put them on the slave rollers instead. Got all the way through the crush, but noticed one o-ring was gone. Found it in the spent grains later.
I deduced that the reason the o-ring is there is to help drive the slave roller, otherwise there is not enough friction to draw the grains into the gap... the rollers are too small.
You may have better luck, but do a search and see all the complaints. Not only about the product, but also the lack of service.
Buyer beware.