I worked on my Redding scale to make it more consistent. The main problem with it was repeatability, even when the same charge was placed back on the hangar. It would have a different reading. No matter where the pan was placed on the hangar platform, the weight would change, so obviously, this area needed alot of work.
In addition to the suggestions Boyd made about leveling and the other tricks he used, the mods I made to the hangar assembly should make your scale work much better.
First, remove the hangar from the scale, then remove the platform from the wire arm. There are small weights inside the platform holder, so make sure not to lose them.
Secondly, take the hangar platform and make sure it is flat. Mine was bowl shaped. Turn it upside down, and using a rubber deadblow mallet, plastic, or rawhide mallet, lightly strike the pan on a flat surface until it sits flat. The soft aluminum will flatten easily.
Third, take the bare wire arm and lay it on a flat surface to see if it's twisted, and tweak until it lays flat.
Next, reinstall the platform to the hangar, and place it on the scale arm. Using a small circular bubble level, make sure that the platform sits level. You will have to tweak the arm a little to achieve this. Make sure that the center of the platform is directly below the attachment wire on the arm when viewed from above so that the weight is placed directly under the fulcrum of the hangar itself.
To check the results, put some weight in the pan and move it around on the platform. It should weight the same no matter where its located.
Its also important to keep the sharp beam angles clean, as well as the contact grooves. I use isopropyl alchohol on the blades, and a hair brush to remove dust from the contacts. Also, make sure the blades are centered in the groove. If they touch one side, it dulls the response significantly. I found that these mods also made my scale much more sensitive to slight changes, such as an individual kernel of powder.
Hope this helps, and Good Luck!