I've been in this home for a year. I have no history on the plumbing work. Drain waste is cast iron. After removing this toilet that started to rotate, I discovered the flange had sheared off. It seems the cast iron riser to the toilet was replaced, but I can't figure out material it is. It has a dent in it that may prevent my Oatey solution from working as the diameter is reduced as a result of the dent. The flange seems like copper, and I can't figure out what material of the replacement riser is. It is not magnetic, so it's not cast iron. The old flange seems to be copper that was welded onto the riser. Could the riser be lead? Can I push or bang out that dent without creating a crack?