my makita 9403 belt sander has a major problem, in mid use the power dropped. i checked the belt and looked for anything obstructing the belt but found nothing. on restarting the sander i could here a clear popping coming from the motor along with large sparks, maybe the motor is burnt out or the brushes are worn? can anyone help

harry, March 2009

It could be a burnt motor, armature of field, or just the brushes. Since the brushes are so inexpensive, I would replace those first and see if that helps. Here is a breakdown of your tool and you can see what parts you need.
http://www.toolsandmachinery.com/index.php?cPath=2213_2300_2301_2315

Don- www.toolsandmachinery.com, April 2009