Hi All,
Seeing as how I work with the Lactina pumps ALL the time, I thought I might
respond to this question.
Yes, something is wrong with the pump.  Both of them.  They should be sent
back to Medela for repair, or exchange, or whatever the ploicy is.
Here at WIC, we had 3 pumps do this same thing (all to the same mom, one
right after the other!  No the mom wasn't doing anything wrong!).  The pumps
all worked fine on minimum, but kick them up to med or max, and the arm would
jerk back, not glide.  The pressure was reduced and the jerking was
uncomfortable to the mom.  We found that the belts on the pumps were bad,
probably from years of use, bad cylinders, or a combination of the two.  We
have taken to trying to test all the Lactinas before we send them out, now!
 Not all moms will realize that there is something wrong.
Just a quick question...The kit this mom used with your pumps, was it the
same one she used at the hosp?  If so, then there is nothing wrong with the
kit.  Just one more thing to look at.

Hope this helps!
Jay
Sac Cnty WIC, CLE