Happy to report I finally found one after about two years of hunting. It popped up on eBay in a large lot of test equipment that was pickup only. I messaged the seller and worked a deal for him to pull that one item and sell in a separate listing. Probably overpaid a hair to make it happen, but happy to have it and it is working even though untested. I replaced the battery pack and got an exact spec Sencore power adapter from a Channelizer 754D listing since they shared the same adapter