Mellotronists

My cheap head demagnetizer that I got on ebay arrived today (Realistic 
231X) and I was wondering if all demagnetizers are supposed to make a 
horrendous racket.  This one barely makes any noise at all.  If I put it 
next to my ear and turn it on, I can hear a faint buzzing, but that's 
it.  Besides messing up your tapes with improperly degaussed playback 
heads, is there any way to tell if this thing's working?  I know, don't 
buy cheap crap on ebay, but I figured that something as basic as this 
would be ok.


john....