As our toilet tank is filling and the float arm is coming up to a finish it starts kind of whining until it finally shuts off.<br/>Is there anything I can do to fix this or should I replace the control unit?"

The washer diaphragm is causing the noise. You can take it apart and make sure it is clean but probably just as easy to replace. No problem to use as is.

Hello Sglshotkw,

I agree with ma0641 the washer at the fill valve will your problem, I will also suggest to check the water level it should be 1" below the overflow tube if not please adjust the water level see the image below, and see if your problem is fixed if not do as Ma0641 suggest close the angle valve under the tank remove the screws from top of the fill valve remove the cap inspect diaphragm if ok turn it over and assemble, good luck.

John