My modular style was overfilling, causing the ice in the hopper to freeze together and eventually causing water to leak out of the dispenser controls in the door. Found that the control dial built into the ice maker had burnt a couple of contacts together and the water would fill for more like 15 seconds instead of the proper 7.5. The fill time adjustment had no effect.
Ordered and installed the factory replacement icemaker and all is well. Just 3 screws and the wiring pigtail. Not counting exploratory and diagnostic time, this fix could have been done in 15 minutes. My refrigerator is 19 years old and the plastic walls have slightly deformed over time, so I also spent a minute shimming the bottom screw so the icemaker now sits level in the freezer.