When rebuilding old tonti forks with the screen door dampers, I prefer used to new. That said, the dampers need to not leak oil while still having oil in them. They need to have no dead spots and have smooth action up and down their entire length. If they meet those criteria, I do not care how "weak" they feel. In my experience, new dampers have too much damping. Every time I use them, I regret it because the front end becomes harsh. I'm more than willling to use one used and one new if necessary. YMMV, and I realize I might be in the minority, but front end compliance is very important to me.
