My brother has a Bosch 12" SCMS. He says the dust collection used to work. Now it's all over the place. He's checked the obvious, dust port, cleaned the bag with an air hose, pulled the blade to check for an obstruction under the guard, all nada. I asked about the blade condition. He said it had a lot of pitch build up behind the teeth ( a 99 toorh Bosch blade) The only thing not changed is the blade. I told him to try either cleaning the blade or replacing it. Anyone got any other ideas? And would the build up of material on the teeth affect the dust collection?