Possible Clues:

• Many marshals handle part of an engine
• Rotating part of engine
• Car engine part
• Engine part often connected to a flywheel
• Vital component of an internal combustion engine
• Eccentric folk handle component of engine
• Auto-engine part
• Eccentric people have Henry behind main rotating rod
• Part of engine nutters originally fitted in Derby, perhaps?
• What will turn when driving constant rates by handle