help me out please.

I just bought this machine and the first day I take it out, it starts humming constantly no matter which part of the sand I put it on. It does the same thing in the air. I read the manual and did everything it told me to. Can anyone help me with this please?

I found a really strange nickel today. It is a 1942 nickel with no mint mark, seems normal right? But when I took it too my local coin shop they told me it was silver, with the same metal composition as a wartime nickel. Today I also found a quarter from 1972 in Philadelphia's mint that had...