Sony Camcorder VX9000 Stuck Iris

If the service manual does not show it as an individual part it is probably not available. Long ago I saw this problem on panasonic VHS camcorders. The Iris assy. was replaceable, but with very careful disassembly and cleaning it was serviceable. I would usually find oil on the individual thin film-like parts causing them to stick together. I disassembled the iris parts, cleaned with solvent, then put it back together using cotton gloves to keep skin oils off the parts when putting it back together. This may or may not apply to your camera and keep in mind that it could lead to total destruction of the iris.