Product review (1 stars): Knocking/tapping sound solved with a different part#!
As many reviewers have said, this is a great ice maker!  Some reviewers mentioned that the machine is loud...making knocking/tapping sounds as it runs through its cycles...a problem we continued to experience.  After replacing the icemaker once, and fussing around with the gears and freezer temperature, I revisited some of the informative customer reviews (there seems to be no obvious way to contact the manufacturer).  After digesting all the information I'd accumulated, I reached the conclusion that the ice cubes were too large for the machine to easily heat, release and push out to the bin.  To make matters worse, the instruction sheet directs you to increase the fill time/ice cube size!  As a result, the gears slip (knock-knock) and eventually the mechanism fails from the stress.  The solution:  remove the front cover and turn down the fill time/cube size by turning the adjustment screw clockwise, moving the adjuster to the left (toward the minus marking).  I moved it as far as it would go without forcing it.  End result:  ice cubes are smaller (and plentiful), the process is quiet, and...the machine is happy (as are those of us who did not welcome hearing knocking sounds at 2 in the morning).

UPDATE MAY 17, 2018:  before long the noise issues returned and ice production slowed to a crawl.  After suffering through two of these machines we decided to take a chance on the identical-looking one with a different part# (241798224 Ice Maker for Frigidaire Refrigerator).  For some reason...this different part # machine works perfectly...runs quiet and produces lots of large ice cubes 24/7 until the bin fills to capacity at which time the maker switches off.  All this, and it costs less too!  We may buy a backup to support our 30 year old Kenmore!