Yes - on your advice I started there but having a hard time finding folks and so looks like have to send it in somewhere and between the initial quotes I am getting + shipping both ways + believe it or not there are handling fees and such (business must be good)... it's running up a tab $300-$400. Which I guess I can see the math - I saw a recone kit for $80, add labor hours @ whatever rate (west coast rates are crazy) and all the shipping and handling - I see how that adds up and especially if they got enough local biz and not enough parts then they don't necessarily care if this prices me out, esp if they got more frequent customers that aren't "hobbyists". So I'll have to give up the desire to preserve the original setup... for now. When Jaco Pastorius and Victor Wooten ask me and my 4 kids to tour with them, I will definitely get this amp souped up ;-)
I haven't had the greatest luck with recones. An EV 18B I hard reconed was very sloppy and the voice coil was dragging. The shop told me to shim the frame. Shimming worked for a short period of time, but after a day or so the voice would start dragging again. Eventually I sent the drive to Electro Voice and the job they did looks factory, and the driver has been good for a long time.
The other driver I had reconed was a JBL E120. When I bought it, the voice coil was burned and stuck in the gap. The recone worked for a long time, but if the driver experienced a mechanical shock, the voice coil would sometimes stick to the gap. I was able to remove the driver from the cab and work the voice coil loose a few times, but my guess is this probably deforms the voice coil bobbin. When I had the cab shipped back from Germany the driver was working fine. When it arrived, it still made sound, but the voice coil was totally locked in the gap. Rather than recone it a second time, I went to a local shop and traded it for a used E120 with the original cone. It's not a 100% tone match for my other E120, but very close.
IMHO if you want to retain the original voice, either get the driver reconed or find a good clean used OEM driver. If you are okay with changing the voicing a bit, get one of the drivers Agedhorse has recommended.
In selecting a driver you need to consider the driver's voicing: mid range and treble frequency response. You also need to consider the driver's Thiele-Small (T/S) parameters. TS parameters describe the drivers electro-mechanical qualities. The TS parameter need to be compatible with the cabs internal volume and port dimensions (if any). I believe you indicated this cab is sealed which tends to be a bit more forgiving, but you still want to choose a driver that will work well in a sealed cab.
A driver's data sheet typically gives it's RMS power handling. This is essentially the voice coil's thermal rating. If the average power goes above the RMS rating for an extended time, the voice coil will burn up.
With bass cabs you need to be concerned with low frequency mechanical power handling which is determined by the driver's T/S parameters and how the cab is tuned. The T/S parameters and cab tuning also determine contour of the low frequency response, and where the response drops off.
Back in the old days it was necessary to calculate all of this stuff by hand. Now the box volume and port dimensions are loaded into a computer program, which does the calculations and spits out a model with lots of graphs and charts.
Most of the Eminence professional drivers have a cab design document that models the driver in a variety of boxes. I will attach the spec sheet and cab design doc for the Delta 15A for your review. Keep in mind the cab parameters in these designs probably do not match your amp perfectly.
