I have a Medela PIS that I bought new 7 months ago. I used to be able to pump 5-6 oz in a sitting, and now I can barely get 1.5 oz max, usually only 1 oz.
I notice that I don't have a problem letting down, but after a the first few squirts of milk everything stops. I can get a little bit more milk with massage but nowhere near as before. I nurse 7-8 times a day and pump 2-3 times a day.
I pump to keep up my supply because 4 months ago (!) DS started a nursing strike that never quite ended...he nurses when he's drowsy (but I have a hard time getting him to take a full feed before he falls asleep), and with lots of coaxing I can get him to nurse maybe 2-3 minutes awake provided he gets a quick letdown. Sometimes he'll nurse longer if I turn on the TV so he can watch while he eats He is a voracious solids eater (though I've cut back on them), and I have to keep on breastfeeding for another four months because he refuses to drink any formula. Between his distractibility/disinterest and solid food I'm really stressing out about my supply. He gets really frustrated when he's nursing and there's no milk.
Anyway, back to the original question...I tried replacing the valve and membranes and it was a little better, but I still am wondering what's going on. I drink 3 cups of Mother's Milk Tea daily and take 8 capsules of fenugreek. I think that there is still milk in my breasts when the pumping output stops, but I can't be certain. Could the motor be wearing out already? Ideas? Tips?