IMO, the basics of scale tuning involve several steps. First of all, it is a good idea to adjust your scale pan holder weights so that when the scale frame is perfectly level, the beam indicates that the scale is in balance. The design of the 5-0-5 makes this difficult. For those, I put a small level across the top of one of the agate retainers. The next thing that I usually do is remove the agates that the knife edges sit on (this would be unique to Ohaus Lyman and RCBS) and clean the socket and all sides of the agates with alcohol and a Q tip. The last time that I did one, I used a Dremel type tool and a small cotton buffing wheel, without any abrasive to work on the agate's V, where the knives rest. I also polished the faces of the knife edges a little the same way, being careful not to blunt the edges. Most of the scales that I have worked on needed to have their knife edges tuned up. I use a diamond lap for that, and then polish with a fine stone, and deburr the edge with a small piece of wood. The steel is not very hard. One thing that I have noticed is how edges can become dulled by how the scale is assembled. It is very easy to hit one of the agate retainers with a knife edge when placing the beam. Recently I have been putting in one end of an edge, running it over to the retainer, holding it there, and carefully dropping in the other edge. Another area to look at is the wire bail that supports the pan holder and rides on its own knife edges. I spread that piece so that it cannot shift , but not so much that it rubs excessively, just a close fit. I usually take it off open it up, put it back on, and then carefully close it a little to get the fit that I want. Each time that I set up a scale, I lift the entire pan assembly by pinching the holder hook just below the bail, and lifting the assembly a little and setting it down so that the knife edges are at TDC of the wire circles that they support. I also shift the beam so that the ends of the main knife edges are not rubbing. The last scale that I did a little tuning on was my recently purchased RCBS 5-0-5 and it now will deflect a little for each piece of Varget that I place in the pan, moving half the width of the balance reference line for one piece, five equaling a tenth of a grain.