The motor will be held in a clam-shell plastic housing - screws will hold the two halves together - Torx head security screw(s)
See this drawing
http://www.rai.co.uk/art2618li3600HA5E00parts.htm
Motors in these things are usually very reliable and long lasting - I would guess that you may have a problem with the battery (battery charger) especially or operating switch (less likely) rather than the motor.
Amazon will sell you a set of Torx drivers.
Good Luck..., January 2016
