Its the piece on the starter motor shaft that is a very course thread that the pinion runs along and centrifugal force throws the pinion into the flywheel ring gear and makes the engine turn.When the battery is a bit flat the shaft doesn't turn fast enough and the pinion can attempt to climb the ring gear and jam so a hit in the right place with a hammer can often release it.I don't know about Spotty coughing but if it happens it may make you cough and say dash it as well
