Further to my previous question, I have determined that the problem is due to the motor armature moving back and forth a little in its bearings, causing it to actuate the speed control governer suddenly as the armature moves. I also noticed that the hex-screw that retaines the fan/governor assembly to the armature shaft was a little loose.
Could the governor slipping a little up the shaft be causing the problem? And if so, if I alter the position of the fan/governor to remove the free-play, would that (as seems logical) alleviate the problem?
George
December 2006