Home Distiller

I am running my first rum, nice and slow , making 200ml cuts, at 180F or 80C thereabouts, I get this funny smell, it is like molasses and copper (although I seasoned copper by first soaking it in wash then minced it with vinegar water) well maybe not copper but something metallic and not exactly easily detectible. I cannot taste it in final product but it does stink a bit.

Any suggestions?