I'm no expert, but this looks as it should and seems to operate okay. Perhaps other members with more knowledge on the disa can chime in to confirm? At the very least, you may have eliminated this as a potential source of the 'rattling'. I would put it back, ensure there are no vacuum leaks (seals well), crank up the motor and investigate further. Sometimes, putting a long handled screwdriver on the area of the 'rattle' and the other end to your ear or jawbone will give you a 'cleaner' sound and isolate the source of the noise. Sounds strange I know, but it does work well in my experience.

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08/06 build 4.4i Stirling Grey over black