The pair with the frozen woofers... I'll bet 10-to-1 that the magnets have probably shifted. I've seen several do this, and have managed to fix most of them. It ain't easy- sometimes it takes removing the whole cone assembly, shimming/epoxying the magnet back on, and putting the thing back together with a new spider and surround. A few times, I've gotten lucky, and have just managed to pull up the loose magnet a bit, squeeze some epoxy into the broken joint, and re-center it "by hand", moving the coil in-and-out to verify clearance. I would NOT recommend this to ANYONE who hasn't done it before, and/or who has an IMMENSE amount of patience and dexterity... it's not an easy job.
On the pair that seems to work correctly- unless the voice coils have been burnt and warped (unlikely, IME), you'll just need to re-foam those. Speaking from extensive experience (I'm collecting EPI woofers for a project- I've got like 21 EPI and Genesis woofers at this point, out of 24 that I need), those are a real cinch to repair... one of the easiest possible re-foam jobs.
Word to the wise- even IF the rubber surround on an old EPI LOOKS OK, CAREFULLY inspect it for weather-cracking where the surround "turns the corner" from the roll to the flat parts... they often start cracking there. Also, the rubber surrounds have a tendency to get stiff... by this age, it's unlikely that any of them will still be as compliant as they need to be (resonance will probably have gone up from 28 Hz to something like 35 Hz or so). I've gotten, to where as a matter of practice, I just refoam EVERY EPI woofer I'm planning to use, using FOAM surrounds. EPI did this themselves, in all the newer models of the classic series speakers, so I feel justified...
Regards,
Gordon.