I have a similar toy motor, only mine has the coils above the flywheel with the flywheel running between them, kind of looks like the eifel tower. Were you running yours on a 6v lantern battery ? I ran mine once on a large old style 1 1/2 volt. Mine just locks up on 6 volt. Did you ever find out any further information on it ? I attached a picture ( I think I was successful).
H&K made quite a few different styles of these motors. I have one of similar design myself along with an H&K Electric Engine. The Electric Engine has 1905 patent dates and the motor was patented in 1908.
Inside the Electric Engine there is an old fashioned 1-1/2 volt ignition dry cell. These can still be bought from battery suppliers, but they are expensive, made in China, poor quality, and don't last very long at all.
New reproductions of these dry cells that use two D cells inside are available from time to time on eBay.
Your motor was also built by H & K as well as mine. Mine runs right along on 1-1/2 volts and will really sing on a small 9 volt battery.