Is pot metal magnetic?
Similarly, does magnet stick to pot metal?
Pot metal is a zinc/aluminum material so you do not have pot metal. Only non-magnetic you might run into that will confuse is stainless steel. Stainless alloys are non-magnetic, weakly magnetic usually.
Consequently, how can you tell if something is pot metal?
If you have a true pot metal that is largely zinc, then you can heat it up and watch the color of the smoke. If it is white, then it is likely pot metal. You may also be able to tell because pot metal melting temperatures are pretty low in comparison to those of other metals. You may also weigh the metal.
It is possible to tig weld some types of pot metal but it is tricky. If the part is not replaceable I would suggest taking a mold of it before starting. The reason pot metal is used for injection molding parts is that is is so very fluid when melted.