I had one break on me like that last year, so now I keep a spare in the boat just in case it happens again.

I got a replacement at my local boat dealer (R&W marine in E'town). It was only a few bucks.

I attached it back the exact same way the old one was. Mine had broken in the middle of the string, so I was able to see where and how it was attached to the TM. It was pretty simple to do.