Hi there mialorena08. Did you replace the brushes just for maintenance or was the saw running poorly? If the saw was running badly before it's possible that you have a bad armature. I would probably take out the brushes and inspect the armature's commutator (where the brushes contact it) and look for damaged or burned bars. Marginal armatures can tear through brushes very quickly.

Hey mialorena08,
Sometimes it takes a while for the new brush's to seat link removed it for a few minutes and see if the sparking subsides..also check and make sure the brush's are sliding in the holder all the way..[so it has enough tension]..you can also take out one brush and turn it over and reinsert to see if it will seat in a little better..[an old repair trick].. if nothing changes and it starts running slower you may have a problem with the armature..
hope this helps...:)
Craig

Hey mialorena08,
sometimes it takes a little while for the new brush's to seat or wear in..if the armature has too much wear already they may not seat in at link removed the tool for a coupla minutes and see if the sparking dies down..if not a repair shop can sometimes fix the problem with a seating stone..
hope this helps...
Craig