The pics as you present them, Richard, are fairly crudely pixelated when you enlarge them. You could have a go at rescanning, with a higher resolution, but even that will always reduce some of the original image into (admittedly smaller) pixels. At this scale, I don't think any amount of contrast and sharpness enhancement will turn the block pixels back into letters.
Your best bet, I think, is to look at the original print you have, with a good magnifying glass, or - preferably - a jeweller's loupe of the kind that looks like an eggcup, and you bung over one eye.
