You should first try if the driver is really gone or not, maybe it's just a wiring problem, also there can be something wrong with the cross-over network. Check the tweeter with a multimeter, if you don't see something between 2-16 ohms, you need a new one (or two, you probably won't be able to find the original part, so you'll have to change both left and right channel drivers) but if you see the desired impedance on the meter, check the internal wiring, crossover solder joints, capacitors, etc. I hope this helps.