If you give repair work a bit of a try, the experience might shine a light on something new that you can take forward, even if you can't fix it all the way.
Very good advice. I was considering that for my own site yesterday. It'll be a very good chance to find out if I know google's algo as well as I think I do. If I can recover it then I'll know I can proceed with confidence in development of future sites. If not, then I have a whole lot more studying to do. So far I've only had to recover 1 site from page 2 back to page 1. That wasn't a big enough challenge to test my understanding.