Thanks for the suggestions - it seems like it will be an easier task to grill these nicely - the cat grilled up pretty good too ; ).
I have to admit not being sure what the motorboard/motherboard is. It does seem that I could pull out the speaker and reset it with grillcloth and a gasket sandwiched between the cabinet and the speaker frame.
I believe the speakers are '75 vintage, but the seller wasn't certain. he had aquired them in a lot with khorns and la scalas and, after getting involved with refinishing and tweaking the other speakers, decided he didn't have the time/patience to work on these. The cabinets are a little rough, so I eventually will probably refinish them and plan to make a few of the tweaks suggested elsewhere on the bb, although right now they sound amazing. I'm running them off a 12-watt Stromberg Carlson that belonged to my wife's grandmother and was about to be thrown out when her house was being prepared for sale. A friend who makes electric guitars and refurbs amps spent several months recapping the amp, replacing resistors, etc. I'm sure I'll eventually run the Cornwalls on a spicier tube amp, but at the moment I have the best $500 stereo in the world. And I'm having too much fun showing my audiophile friends how good the 40-year-old dust bucket that belonged to a little old lady from Norway, Maine and was headed for the garbage can sound with a $120 investment.
As for the cat "not being in the know," that may be changing. My listening chair has become his favorite seat in the house since I hooked up the Cornwalls. He seems to have a particular affinity for Grace Jones and Marc Ribot (my reference disks).
Thanks for all of your help.
Other suggestions for tweaks and modifications are more than welcome.