I'm still going for engine tenter, who was someone who looked after a machine
Dictionary of Occupational Terms
http://doot.spub.co.uk/idx.php?letter=Eengine attendant, engine driver, engine man, engine minder, engine tender, engine tenter, power engine man, stationary engine man, stationary engine driver ; driver (engine), engineercontrols stationary engine by moving lever which switches on power-drive, by turning tap or valve which controls gas or oil supply or supply of hydraulic power or other means; watches gauges, indicating steam pressure or other power-units generated, regulates engine's speed of running; cleans and oils engine by hand, or fills lubricating cups, seeing that oil feed apparatus is working correctly; sometimes also cleans, oils, and generally attends to plant running in connection with stationary engine, e.g. fans, pumps, compressors, etc.; usually does minor repairs, e.g. fitting new piston rings or gauge glasses; sometimes capable of overhauling and doing heavy repairs; sometimes specifically designated, e.g., electric engine attendant, elevator engine man, gas engine attendant, hoist engine man, hydraulic engine man, lift engine man, rolling mill engine driver, stamping engine attendant, stamping engine driver (pulverising ores), ventilating engine man.