I agree with Tvad - tube dampers are no cure for sick tubes. Their primary purpose is to assist healthy tubes in presenting micro details for clearer images. They aren't what you need in this case.
A minor amount of microphonics can contribute to a soundstage appearing slightly larger than normal which on some recordings can be a positive thing. However, when they get to the stage that you are describing, they have gone past the positive effects and need to be replaced.
A minor amount of microphonics can contribute to a soundstage appearing slightly larger than normal which on some recordings can be a positive thing. However, when they get to the stage that you are describing, they have gone past the positive effects and need to be replaced.