Returning to photography after 2 decades of being really busy. Resurrecting a Braun F90O which I bought some 40 years ago new which needs some TLC. Needs a replacement battery and ideally if I can lay hands on one a service/repair manual. Last time it was used it did work but the batteries being dead and no longer available, have toyed with making up my own battery pack. Anyone out there that can help with this. The battery does not ned to fit in the original casing as the intended use will be in a static situation. A service manual would be very useful in case there is a component failure e.g., capacitor that may need replacing.