A plug for retaining a filter screen in a fluid port of a servovalve, comprises an annular body, the annular body comprising: opposed first and second axial end surfaces, a radially inner surface extending between the first and second axial end surfaces, a radially outer surface extending between the first and second axial end surfaces and at least one recess formed in the radially inner surface for receiving a tool for removing the plug from the port. A tool for removing the plug comprises a pair of handles pivotally mounted to one another about a pivot, each handle having a plug gripping portion extending therefrom beyond the pivot, each plug gripping portion comprising an outwardly projecting tooth for engaging in the recess of the plug when the plug gripping portions are moved apart by operation of the handles.