My tank rattles what should I do?

The tank rattling suggests that the barrel weight (part 32) has come loose from its retaining clip. A loose weight shoul have no impact on running, but if you would like to put it back in position then gently ease off the barrel end (part 6) with no ladders – please take care not to damage any of the detail while doing so! Slot the weight back into the clip –  you may wish to use a small amount of superglue or epoxy to secure the weight. Refit the barrel end.