Old Lionel NW-2 switcher

I have an old Lionel switcher and it makes a loud ugly sound. Almost like it is blowing a rundown horn. It does not have sound in it. I tried to clean it. When I did that it did not work. Me and my dad fixed it and got it to work but it makes that sound. If anyone has this engine please tell me and some tips on fixing it. Even if you don't please speak up.

Here is a picture: