I haven't check the water supply yet. / Yes, the icemaker was full of ice but the cubes had not been harvested.
Further info: Old/inop icemaker is part# WRX30X0241, electro-mechanical unit. The cross referenced replacement is part# WR30X10093, so you are correct.
What I have done: Been reading a lot on the site and researching part numbers. Also cleaned the coils on the bottom of the fridge (they were due) and checked that the evaporator fan in the freezer compartment is running properly. I also put two ice cube trays in the freezer filled with water to find out if the freezer compartment was getting cold enough to make ice - it is. One point though, when I checked later this morning, the ice cubes in the tray were somewhat melted together so it could be the defrost system is staying on too long.
I'll check the water shut off valve, but my educated guess is that it is the ice maker, since it had a full load of cubes in it (water had to turn on to fill the tray) but was not harvesting when I noticed it was not making ice..