If it is a flanged bulb, Peter White may still stock them.

At least one of my old generators uses a threaded bulb ("miniature Edison screw base", I think). No idea where you find these.... they were hard enough to find back 30 years ago. The best bet is a bulb designed for a flashlight. They were designed to produce a lot of light, but not for a long time. I think 100 hours was a typical advertised lifetime for the standard dynamo bulbs. If a bulb is designed to last longer, it won't operate as hot, which increase lifetime but greatly reduces the light output.


Steve in Peoria, with a few of the flanged bulbs in the parts box