All possible - but low battery volts will cause the starter to spin without engaging the pinion. If the battery has a dead cell, even a jump start won't compensate.
phil_saunders(a)bigfoot.com
Phil Saunders, April 2009
Either the starter motor is loose, or the ring gear on the flywheel is very worn ( both unlikely) or the drive pinion on the end of the starter motor has worn away (very common for most of the teeth to be sheared off).
