Yes, there is a thread somewhere. Take it to a dirt track shop and let them tighten them. In cycling this is normal procedure after a couple of miles. Don't know about bikes, have not had spokes except on my Honda MT 50.
Routine maintenance on any bike with spoked wheels. You can tap them with a spoke wrench and listen for a "ting" sound or a "thud" sound. Snug up the "thud" gently until is is a "ting"......you have to crank on more than one spoke to start crewing up the trueness of the rim. Just go slow and easy.
This was part of a tune up back before cast wheels became commonplace.
Spoke wheels cost a lot more to produce than cast wheels.....