I bought an old unopened Bachmann CSX Dash 8-40cw DC at a flea market last summer. I was planning to convert it to DCC with sound during this winter. When opening her up, I noticed a bright green corrosion like you find on corroded copper battery cables. I did a lot of sound decoders conversion on my fleet of DC locomotives and they were all made from aluminum or magnesuim alloy. However, this one looks like its made of copper because of the color of the bare frame when I scraped off the corrosion. I'm planning to cut/grind the frame to fit a speaker. After the cutting and the grinding, I will spray paint the frame. My question why copper? When did they change over to the other alloy? Can I cut copper? I never cut or grinded anything copper before.