Looks like the stapler is a scrapper if I can't find a little spring
Dear Mr Sussex,
Thank you for your email. Unfortunately, we dont provide any repair service for faulty items as it is not economically beneficial for customers and we dont have spare parts for this unit. I apologize for the inconvenience caused.
If you need any further help, do not hesitate to contact me. Thanks for your interest with our products.
I'm guessing the spring only serves to return the pin or maintain pressure on the strip of staples so probably easy anough to make. I'd start by looking closely at a clothes peg ...