Just bought a HP-67 calculator at an auction

[mipidc]

I just purchased a hp-67 in pristine condition. It looks like it has never been used. The problem is that it did not come with a charger. Any thoughts on how to test this calculator? I would also like to test the magnetic tape reader as well. I've included a couple of photos of the calculator.
The serial number is 1611a02046 and the earliest known serial number as I have learned about begins 1609 so this was made in the 11 week of 1976 and is one of the earliest units produced. Any more information about this unit would be greatly appreciated. It came with two mint condition manuals as well.