Hi, I picked up a Atco kickstarter spring from this business in the UK, you could try them for a new lever. The spring was for my 14" Atco that I hope to restore soon. It starts and runs, I have cut my front lawn with it a few times. I also have a Scott Bonnar 14" which I also use occassionaly. http://www.oldlawnmowers.co.uk/
