I'm surprised to see a machined aluminum pulley. When I was in the market for a horizontal band saw (the smallest, manual one that they sold) the display model had a stamped steel (mystery metal?) pulley. One of the reasons that I didn't buy a HF unit. What saw is this off of?
In any case---Return the entire saw; even IF parts are available, it will take months to have one shipped from China. As you said, the damage done to the pulley may also have caused some hidden damage that wont show up until 1-day after the warranty.
Mike