I've come up with a couple possible solutions for the depression in the midrange that has been causing a depression in the listener.
The obvious answer is to change the cabinets. I happened apon some 43** style cabinets listed as "JBL "bass cabinets". These have S7 loads and the woofers appear to have been reconed recently with 2235-style cones.
But there was a caveat (as always). If I wanted these I also had to take the pair of 4430s. And if I wanted those, I also had to take the pair of 4425s. But if I wanted those, I also had to take a Tascam M-35 mixer.
Both the 4430s and 4425s need new foams and none of the cabinets are perfect.
If it is of interest to anyone, the mixer will go up for sale/or trade (including a trade of labor to refurbish cabinets)? I've not decided what to do with the other stuff. But some may end up here.
They're out there if you keep your eyes peeled.