Fridge is 5 years old. Stopped making ice. I can hear the valve that lets water into the ice maker shut on and off, but just for a split second most of the time. Very rarely it opens the regular amount of time and lets water in, so it's an intermittent problem. When I push the test button on the side of the ice maker---same thing--intermittent. Thinking it might be the ice maker, I replaced that, but it didn't help. Sounds like the system is telling the valve to let water in, but not always for the full amount of time. Then I replaced the water valve and that didn't help either. My question is: Does this sound like a mainboard issue or could it be a temp sensor in the ice room or something that's shutting the valve off prematurely? Or could it be the icemaker circuitboard? I don't want to spend the money replacing either of the boards if it's not necessary, because they are both very expensive. Here's the numbers:

Icemaker: OEM model number: WR30X10131. Samsung model number: DA97-07365A

Circuit board Ice maker: WR55X10764
On the ice maker circuitboard are the numbers: ORTP-708 REV: 0.1

Mainboard: WR55X10985
On the Mainboard are the numbers: DA41-00473A

Any help much appreciated.