Way back in the late 80's we bought a  "Big Hauler" set for my son. The locomotive is a 4-6-0 with a number 7 on the side.  After a few years we put it away for our grandkids!!  Well now the time has come to resurrect the set for under the Christmas Tree.  My only problem is  the directions have been misplaced and my memory is shot  so can someone please tell me "WHERE DO THE BATTERIES GO"!! in the locomotive!!  For the life of me I cannot see where they go nor can I remember!! 
Thanks