Bosch SHE46C05UC is noisy at startup and...

My Bosch (which is suppose to be very quiet) is very noisey - almost a rattle or trying to work hard sound at the very beginning of the cycle and then through various points in the cycle - it appears to tie in with water release.  Had some blockage but cleared that and since then, this will not stop.  Could the pump be the issue?  It only lasts for 20 seconds at a time.  It is also connected to an air hose at the sink.  The dishes clean just fine but the noise is driving me crazy.