The only place a magnet sticks to it are the fly wheel and the silver parts so I guess that means it's aluminum, although it's still pretty heavy. I bought it, so now I just have to play with it. First order is finding a new drive belt as the one that's on the machine is cracked rubber and probably won't last much longer. Other than having to help it start off because the belt is loose, it stitched quite nicely and runs pretty quiet! I've only had electronic machines since the 80's so this is going to be interesting.
Thanks for all your help everyone.