So this one took a little detective work...
First, I assumed there was an issue with the water valve solenoid. Easy to pull the front kick plate and see the valve, but the tight space made it pretty hard to actually access. I pulled it off and tested the connectors with my volt meter to make sure it was getting power when the switch was depressed (it was not.) Had to use a couple of male electrical spade connectors to insert into the molex body for the volt meter leads. Glad this wasn't the issue because this particular valve is discontinued...
So, next assumption was that it was the micro-switch. Off came the door handle, the cabinet faces (this is a built in), figuring how to remove the dispenser front plate, and there it was. The micro-switch was fine, but the plastic mounting pieces for the switch on the base plate had all snapped off and the switch was just hanging there. Not a great design to hold that switch, but probably pretty easy to assemble at the plant. No way to field repair this - only real solution is to replace the plate.
Part came pretty fast -- 2 days ahead of earliest expected day -- and I had the entire thing back together in less than an hour. The plate is held by just 2 screws and all of the electrical connections are small molex fittings.
I was surprised that this part was still in stock, and thrilled at the price. Wife is happy that the fridge is fixed (do you know how hard it is to live without a water dispenser?) and all done for a fraction of a service visit!
Thanks AlliancePartsPros!