I never had the trouble you describe in letting down for the baby, thank god,
but because I was working I pumped every evening to keep up, and with both
kids I found after about six months that I had great difficulty letting down
to the pump before bed at night.  Tried all the "think about the baby" tricks
and it only got worse -- I was more worried about my letdown, so I didn't let
down -- the same kind of mind game your client is having, I think.

In the end what worked best was to get my husband to read out loud to me from
the newspaper or whatever other interesting thing he had in hand.   As soon as
I actually concentrated on that and completely forgot the dang pump for more
than 30 seconds or so, hey presto, let down and out of there.

Good luck to her --

Elisheva Urbas
NYC