As a temporary solution you can sharpen the old needle on a fine honing stone. If you run your finger nail over the neelde tip, or run it over a nylon stocking you will know which side it catches on. Carefully run it once or twice or over the honing stone and check again if it still catches. It should feel smooth from all angles.
Converting it to 15x1 has a few advantages; wide range of needle sizes and speical tips available. The only dowside is you have to let any future owner know it's set for a different needle type. Put a note in the manual or something.