I've been following this thread since this morning. I'm a pro shop owner and work with both PROSHARP AS 2001 AS and Sparx Sharpeners in the Boston area. A couple of things jump out. First off, blades do not have to be trashed just because you don't know the history. PROSHARP has a process and charts on how to set up the machine for a previously profile blades with either the QUAD, ZUPERIOR or ELLIPSE. If the owner doesn't know or you don't know where the pivot point is, you can use a piece of paper ( I use yellow sticky notes) and on a flat surface, try and located the PP. Now, saying that, I'm not a big fan of this. What I like to do is rebalance, rematch the blades together in the AS 2001. Then I put back on either a 13, 11 or 10 radius. What that does is assure you where the PP is back in the middle before you start a more professional profile like the QUAD's or Zuperior. Now I've also discovered that I can save some metal on the blades if I'm going to put on a ELLISPE by using the previously mention method depending on the size of the blade you're going to work with. I've also started using the Detroit 1 (a 10/20 combo radius) if I'm doing a ZUPERIOR profile or a 10/13 combo if I doing a QUAD. All this is an effort to give the customer the best possible outcome. I have elite hockey players who are D1, D3, USHL, NAHL. NE PREP and NE HS players routinely testing profiles on ice at my proshop. So accuracy is as important to them as it is to me. I hope this helps.