Hi again,
Traderz, make sure that the cap is actually bad using a capacitance measuring device. Using the resistance function on a meter won't work, as all functioning caps will measure with infinite resistance ("open circuit") because they block DC from passing. Only AC signals can pass through caps. If the cap isn't bad and the ribbon is intact, the tweeter can still fail if the internal wiring goes (I've seen this) or the internal impedance matching transformer fails (this I have not seen). I mentioned spraying Deoxit in the L-pads not to fix your dead tweeter problem, but to remove the oxidation that can build up in these (especially in 10+ year-old speakers) and make them noisy and intermittent. I got fed up with L-pads and their sound, so I removed them from the circuit, but I was able to match driver outputs with an outboard active crossover feeding separate amps for the drivers.
I think Brian probably special ordered batches of 1.3 uF caps for his tweeter crossovers from J. Peter Moncrieff at TRT. You can buy 1.0 uF and 0.33 uF caps and wire them in parallel (like the big bundle in the midrange crossover) to match. A 1.3 uF cap with the 6 ohm tweeter (along with the parallel inductor) gives a second order Linkwitz-Riley high pass filter at 10 kHz. I underestimated the crossover frequency at 7 kHz based on the RM/X literature, but 10 kHz is more likely because the stack of six Neo panels are run full-range at the top (no low pass filter on the mids) and have significant output above 10 kHz, but their dispersion is quite narrow at that frequency (unless you install the constant directivity waveguides). Be sure to order the "speaker" version of the caps and not the "electronics" version. Also, orient the TRT caps in the correct direction (see installation instructions, or follow the orientation of the cap that you removed) as they sound worse if you reverse them. And remember, they take a while to break-in. Heck if you've got the money you can go up from TRT and try the Teflon caps from VH Audio or Dueland, but 1.3 uF of these will cost you more than the actual tweeters, and Teflon caps take FOREVER to break-in. If you want to go full monty you can install batteries (24 VDC) parallelling the caps to maintain DC polarization of their dielectric even when there is no audio signal, but then you have to open up the speaker to replace the batteries when they go bad, unless you OXO your speakers (remove the crossovers from the enclosures, install another set of binding posts, and run three pairs of wires from your outboard crossover to separate terminals for the woofers, midranges, and tweeter. And then there is the active crossover option with tri-amplification of each speaker.
BTW, for the James Bongiorno electronics fans among the VMPS crowd, Cullens Circuits bought the rights to manufacture and market updated models of the Ampzilla, Son of Ampzilla, and Ambrosia preamp. They were playing the new Son of Ampzilla at T.H.E. Show at Newport Beach this weekend.
Steve