Hi all. I got a "Naniwa" (chinese?) single phase series AC motor. I tried to reverse the rotor connections (brushes) as I figured out this is the way it is done in hand drill. It is rated 220v/0.5 amps. I connect 2+5, 6+4, and connect 1,3 to 220v AC. Runs fine, 18,000rpm as stated. The problem is, it runs fine in normal, but to reverse, I connect 2+6, 5+4, and 1,3 is 220v. It runs about 11,000 rpm, brushesh spark out , and gets warm soon. My fear is , this is uni directional motor. Is there any way to change winding? I guess need to get my head around winding the motor...just don't have time. So previous experience is much appreciated.. There are 2 symmetrical stator windings, and one rotor with brushes.