KitchenAid Dishwasher Intermittent Soap Dispenser?

Hi, All,
I own a 16 year old KitchenAid dishwasher, model number KUDI220T.
Recently the detergent dispenser fails to open most of the time. (It works about one time out of ten now.)
I suspect that the bimetal actuator for the dispenser needs to be replaced.
I detached the bimetal actuator from the dispenser unit (let it hang on the connecting wires) and watched it during a wash cycle... It is energized during the second half of the "Light-China" portion of the wash cycle.
The bimetal does flex as I think it should when energized, but apparently not enough to release the detergent door.
Does it sound like replacing the bimetal ($22) would solve this problem, or might there be some other cause, like not enough actuating current?
Thanks for any advice!
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