I use the Medela Swing pump when I'm at work. I pump, usually 2x/day 2days/week. Sometimes, depending on client/meeting schedules I pump 3x/day. So, not a ton. I have been doing this since the beginning of June when baby was 6 mo. He is now (nearly) 1 year. I've been using the same pump the whole time with no problems (output has decreased, but I assume that's normal).
ANYWAY, the last couple of days that I've pumped I've had the same problem: the pump is not stimulating a let down. In fact, it barely moves my nipple. This morning, I let it go on the highest setting for several minutes with not even a drop appearing and my nipple barely moving. I tried repositioning it, made sure the hose was securely attached, nothing. I just sterilized all the parts last night. I was able to really massage the breast while the pump was going, do a little hand expression and then once let down happened, it pumped normally--good suction. Then, when I did my second pump session today, there was NO problem at all. It worked just as it should from go. I left the pump set up between sessions, so it wouldn't have been anything different in the set up. This has happened each of the last few days that I've pumped.
Do you think it's the pump or user error? What could I do to try to trouble shoot this? There really isn't any environmental difference between the two pumping sessions.
FWIW, about 6 weeks ago, some milk got into the motor. I followed the directions to clean/air it out. It worked fine, except it would unexpectedly short/cut out during pumping. That problem, though, stopped as suddenly as it started about 3-4 weeks ago.