Diaphragm sticking while pumping - suggestions?

[CharlotteMommy]

I have the Lansinoh double electric pump (same as the Ameda Purely Yours), and have been exclusively pumping without a problem for the past six months. Over the past week or so, I have noticed that the diaphragms "stick" (contracts but does not fully expand) while pumping, and therefore does not produce maximum suction while pumping. I have tried to change out the diaphragms, but this does not solve the problem. Anyone else BTDT and have a solution? TIA!

[stillplayswithbarbies]

have you changed out the small white valves? That is the first thing to go that will affect suction.

[CharlotteMommy]

Yes, I change out the valves about once a month. This is a completely different problem that I haven't encountered before.