Hi Ronald, when I was looking to rebuild some OLA’s, I wound up simply buying two pairs of woofers (and 3 pairs of tweeters) on eBay. I think that’s your best bet. One pair of woofers needed new surrounds (which I replaced, a reasonably easy, but not trivial exercise) and one pair basically was “good to go”. (There was a price difference…) If you go the route of replacing the surrounds, you need to make sure to purchase the correct surrounds. Reading a few of the strings here will turn up the correct replacement, I can’t quite remember from whom I purchased, so I’d also have to look to refresh my memory.
There are two types of woofer that will serve as drop in replacements for the OLA: (1) the actual “Masonite” woofers from the OLA, or (2) the steel face woofers from the “New Large Advent.” They’re absolutely interchangeable and I suspect that the steel face woofers are actually easier to obtain. The original ones have a Masonite face, a brown, 2” wide ring of Masonite on the front face of the woofer. The NLA woofers just have a steel face. I am not aware of any other woofers that are completely suitable.
Searching for “NLA woofer” or “OLA woofer” on eBay will probably bring them up. You may need to be patient for the items to actually come up for sale, but when I was looking a couple years ago I was able to purchase the two pairs fairly quickly.
Good luck!
