Notching drum! oooo bad bad bad.
The spring may not be your problem.  could you specify when the noise 
is made?  A lot of times rears squeek at the shoe contact points on 
the backing plate. that can be fixed by smearing antiseeze on them. 
Also, a slight offset in a return spring or failure to seat 
everything properly can cause unusual noises.  At The 
Brake Shop, (recently featured on the channel four news hall of 
shame) if you came back due to rear brake squeek we would take the 
drum off, make sure all the springs were still in position, bash the 
top of the shoes with a hammer to reseat them on the cylinders and 
adjusters, and send you on your way.  fixed most of the problems.  
Like I said though,  Noises can be caused by a huge number of things. 
a more detailed discription would help greatly in the diagnosis.  
  afterthought.  Although i have never seen one, I suppose glazed 
drums are a posibility.
Ed.