My toilet tank quit filling. If I lift the arm next to the assembly and drop it once or twice the water will fill again.

If you have the float ball on a rod type shut the water off and remove the three screws on top. Lift the float ball and stem assembly out. Now pry out the washer and turn it over seating it in firmly. Now place a pan over the open valve and turn the water back on for a moment to flush out the supply and open ballcock. Reassemble and test. Better now? Good luck, Tom

Don't have the float ball on a rod.

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