I was hoping to get some help troubleshooting this problem with my espresso machine.  It has been working wonderfully the past few months since I bought it used off of craigslist.  I immediately backflushed it with purocaf, and try to take good care of it.  I only make a few shots a day, so it's not under heavy use.  I try to backflush with water after I'm done using it each day, and every couple…