Queen Galadriel and the Nazgûl.

Had Galadriel not passed the test and kept the One Ring, well, do you think she could have somehow disrupted or 'jammed' Sauron's use of the 9 as his servants?

They would have remained his servants of course. He kept the 9 after all.

Those who used the Nine Rings became mighty in their day, kings, sorcerers, and warriors of old. They obtained glory and great wealth, yet it turned to their undoing. They had, as it seemed, unending life, yet life became unendurable to them. They could walk, if they would, unseen by all eyes in this world beneath the sun, and they could see things in worlds invisible to mortal men; but too often they beheld only the phantoms and delusions of Sauron.

Maybe the last sentence would have to do with the kind of thing Galadriel could achieve with the One. Sauron could have given them an errand, but then Galadriel could have 'artfully' disrupted the errand, or bent it to her own purposes. (In UT the Witch-King is shown to be vulnerable to Saruman's voice - that's how Tolkien phrases it - and we know that voice to have been, well, 'magical')