Refreshing a Mignon typewriter character field or keyboard

The 'keyboard' or character-field of a Mignon index typewriter is where the desired character is selected with the pointer. This map or field is a curved plate, covered with clear celluloid. After 90 years or so, on some key-boards, the celluloid is not so clear anymore - and what was worse on this specimen; the old plastic started to crack and crumble.

Because it was falling apart and catching the index-pointer, this 'keyboard' was taken apart for replacing the clear plastic with new. There are a great many tabs around the rim; after carefully bending these open, the stack of a fibre backing-plate, aluminium sheet with the characters and the celluloid top-sheet can be taken out.

A replacement top-sheet of about 81.5 by 128.5 mm was cut from clear plastic sheet. With this new sheet, the difference in legibility is very noticeable. Bending back all the tabs very gently, fortunately only one tab broke off. (If this new plastic sheet will last another 90-odd years before its starts to crumble and needs replacing, then the keyboard has enough redundancy in tabs to last it at least a few centuries ;-)

The index-pointer no longer snags on the keyboard-cracks; smoother sheet, smoother working of the cheap-n-cheerful Mignon :)