With the older Fluidmaster valves (washer in the base), it was possible to fix a fill/leak problem by cleaning/replacing the washer. With the newer 400 Series (washer on top), replacing the washer nevers seems to do anything. Since, as Bob says, you can leave the base in place, and just replace the upper valve assembly, what do you think the chances are of Fluidmaster selling it separately? Better yet, why not address the quality control issues with their valves, and save us all the aggravation!
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