Trackmaster 2 Motor Swap- Help

yeah i put the spring in there but its not actually doing anything as far as i can tell. let me give it another shot

Edit:
ok. its working. i had the gear in the wrong way. although he moves with such lethargy due to the motor swap that i hardly think all this time and effort was worth it. oh well, i'm too in debt to buy a new duck so this will have to do! xD