Studiodog,
I have a couple of tools that are real handy for removing runs. The first is called a run razor, and it is a single edge razor blade that has a base that slides along the panel and has a micrometer adjustment knob that lowers the blade to shave away the run. The other tools are called nib files. These are small pieces of a vixen file that are attached to a wood back block they are about 1.5" square and ae very easy to shave down small runs. Vixen files have curved teeth and only cut in one direction, so you just stroke the file over the surface until it shaves the high spot down to flat. When you are sanding, allways use a very firm block to flatten the run. A softer block will cut the area around the run as well and you take the chance of sanding through before the run is gone.
I will usually use a small block of aluminum under my sandpaper to assure that I only cut the run. The smaller the block, the less likely you will sand area arround the run. You can get the runrazor and nib files at most body supply stores, and I believe that I saw them in Eastwood's catalog, but I couldn't swear to it.
Regards, John McGraw