where is problem

[john]

Have 385 motor tool about 15 yrs old which has seen very little use. I just finished a small grinding job and turned the variable speed switch off. About 1 or 2 seconds later I heard a loud "pop". Needless to say the tool would not work thereafter. Any ideas as to what happened?

[Dave]

I know that when that sound occurs while running, it means the rectifier and speed control just went to the Big Workshop in the Sky... probably because the armature is bad. I repaired my speed ctl several times, but it was never quite the same. I miss it...