The punch pin on a slate guillotine is replaceable.
It doesn’t cost very much, although with normal usage it’s rare to have to change the punch pin. If you do have to replace yours for whatever reason, replacement pins should be available from the manufacturer, or occasionally the suppliers.
Step 1 – Unscrew pin
Using a spanner that fits around the locking nut of the pin, unscrew the whole pin from the handle of the slate guillotine.
Step 2 – Replace pin
Remove the old pin and put the new pin in its place, with the sharp point away from the handle of the guillotine.