Does anyone know what size the allen head screws are that attach the J&M headset to the helmet are? I had one screw fall out and I can't find that small of screw anywhere around here. I can order a whole parts kit from J&M which includes the screws & nuts, for $16.00. But all I need is the one little screw & nut. I can't even tell if it is a metric or american standard size.