Find some appropriate rechargeable nickel cadmium size c batteries or adding battery management system and replacing those with lithium ion or lithium po. It allows for external powering via the two DC inputs and I have a bench power supply and it's the standard barrel type of inserts but I really kind of want to get the batteries all replaced and soldered in place and have everything as check everything a little bit better look at some of the caps so little closer test them a little bit and see if there's anything dramatically wrong with it before I power it up....

As I said I really want to look at the capacitors even though it is meticulously well cared for there's not a bit of dust inside this case and I still want to test some of these old capacitors to see if there's anything straight up bad but nothing has leaked and there's nothing fouled that's directly obvious but as you can see from the photos the it's old school PCBs