If the pin had come out of the disc, leaving its socket hole in the disc intact, and the pin unbent, the best solution is to solder it back in. At least that has always been successful for me.
Anyone who does electronic repairs should be able to do that without harming the plating on the disc.
I have had challenges with parts from L&H. As of my last contact purchasing (about a year ago) the procedure was: call L&H West — they now hold stock on all the parts. But the information about _which_ part is needed, part numbers, descriptions of parts, is still in Chicago. You can eventually get the parts you need, and perhaps they have smoothed up their internal procedures by this point.
All this assumes you know exactly how to remove the disc, replace the disc, and get it back in regulation. If not, you need a harp technician, who can handle all of the above for you.