Techniques for modifying an image may be applied to heal texture areas within the image. The hollow member has a first clamping surface along an edge of the window, while the closure member has a second clamping surface opposing the first clamping surface and disposable substantially adjacent thereto in a clamping or closure configuration of the instrument. The lower motor cover is configured to be assembled to one of a plurality of upper motor covers depending on engine size, and each upper motor cover is configured to be assembled to one of a plurality of top caps depending on whether the engine uses an electric starter or a pull starter. A second cam drive gear is mounted on the first camshaft in an axially spaced relationship with the first cam drive gear. The thickness of the first organic layer and the thickness of the second organic layer are both larger than the thickness of the sacrificial layer.