We have purchased two DeLonghi burr coffee grinders now, one "retro" style and one regular.  We also bought one for each of our grown children for Christmas, as everyone is into grinding beans at the moment.  Unfortunately, all these grinders had to be returned for the same reason...the beans would seem to get stuck in the grinder, causing the motor to whine with nothing to grind, until the unit was shaken to dislodge the bean.  We then bought a Krups burr grinder, and had the same problem.  We've since done a lot of searching, and have realized that in order to purchase a burr grinder that will really do the job, which includes grinding properly for espresso, one has to pay somewhere in the area of at least $200.00 and up.  I guess we'll save our money and just keep using the blade grinder for now - it does an ok job for use in a coffee maker, but does only one grind.  We will wait until we can afford a really good burr grinder so that we can do our own espresso grind.  Hope this helps someone else looking for that cheap but great burr grinder - I don't think it exists.