Zinc will react to muretic acid , just a drop ,it will dance a jig on zinc lesser on an alloyed metal of sorts no reaction on lead/tin/lino.Take normal safety steps handling the acid !!!
Not cadium ,it`s to expensive to put on wheels just to be torn/slung off .& cadium is more toxic than lead !!
Look like weights of of an import of sorts , they maybe aluminum ??
Lyman provides an adjustment on most of there furnaces , remove the knob, some have a set screw some slide on , look at the shaft is it hollow ?? if it is take a small flat bladed screwdriver & insert it it`ll engage the adjustment screw , can`t remember which way to turn it though .