Make one attempt to give them the chance to make it right, to YOUR satisfaction, and if they do not, or try and blow you off, then go straight to small claims.
Sue for the total cost of a re-cone job. They will argue that they are only responsible for the work they did and that the voice coil, motor etc could have already had troubles brewing (you know they will). (The judge will definitely ask you how you arrived at the amount. Just explain it; don't be intimidated.)
But that's BS unless they had you sign off (or spoke to you on the subject) on potential hidden damages or a preexisting condition when you picked up your drivers. Even that is a weak argument with a good judge: "well then why did you perform a repair and take payment for it if the item being repaired was already inoperable"? Understand me? You will win.
I don't know all the nuances of consumer law in your state with regard to the awarding of damages, but YOUR argument in small claims should be "good faith".
I assume that when you went to pick your speakers up and paid them their price you were fully expecting your transducers to be in good, if not top, operating condition.
In fact, I know it. Stand your ground and "tell it to the judge".
They broke your shit. Make them pay.
I'm so sick and tired of half ass workmanship and disregard for quality in this country I could scream.
Get busy.
Let us know how it turns out.
Jim