The pins on the ignition cylinder had been removed by a previous owner, so that any key would work. While this worked fine for turning the bike on and off, without pins there was nothing to hold the key in the cylinder while in the on position. New ignition cylinders for this model are either unobtainable or ridiculously expensive. I ended up purchasing a key of the correct type online. The fork lock was frozen solid, so I ground the cover off of one pin row and removed the pins and springs. Using a combination of pin drivers and springs from the fork lock and pins I carved out of a small nail, I was able to construct a working ignition lock cylinder. The pin cover is currently held on with zip-ties while I find a suitable clamp or steel tie. However, when the side cover is replaced the repair is invisible.