Try and catch it right after it fills up. Look and see if all the slots for cubes are actually being filled. If the front one or two slots aren't getting water then it can cause the IM to go through a second fill. It has a thermostat which is sensing the front of the mold. If it doesn't warm up upon water fill, and open, it can cause the IM to go through a double fill.

Sounds crazy that a underfill can cause a overfill, but it isn't a uncommon scenario.

If this happens to be it, you may be looking at a water valve that's going bad. There also should be a adjustment screw on the side of the IM head that you may be able to get enough adjustment out of.

So you're saying that while the ice is frozen in the mold, ready to be harvested, all of a sudden the IM calls for more water and another 4.5 oz. comes pouring in?

Not a real common scenario for a IM failure. Have you tried moving the rakes(paddles), are they stripped, as in they move around freely?

Is it possible the water is just constantly dripping in after it's filled itself, eventually causing a spillover?

If water came in without the unit being plugged in, it sure sounds like you've got a bad water valve. It just isn't closing off, and it's letting water come through.

Part number: AP4298908

Sounds like you put the wires for the dispenser on the IM solenoid, and the wires for the IM, on dispenser solenoid.

You've got something mixed up, be it the wiring or the four different plastic lines. The plastic line coming off the main valve that your house plumbing hooks to should be going to the water filter. A line from the filter should then be coming back to the single connection to the dual valve. Then one side of the dual valve should go to the IM and the other one should be going to the dispenser.

Don't know if it will help or not but on the below link if you look at pg. 11 and 12 it shows a wiring diagram and schematic. They aren't real clear so seeing them may be an issue.

Model PLHS269ZDB3