I've just bought two QTFX-700 smoke machines for use in an upcoming production. One of them runs fine and hardly makes any noise at all when it's running. The other one seems to be producing less smoke on each burst and when the button is pressed it seems to make a strange noise, almost like a grinding sound. Any ideas what could cause this and how it could be fixed? I haven't been able to get in touch with the manufacturers and I need the machine soon!
Cheers for your help,