make sure you put everything back together right chances are somethins just in a bindif u cant find anything take it apart an turn the car on to see if the servo still works in both dirrections
If you plan on using the car outside do not use the lube on the differental. You probably just need to loosen up the steering knuckles. Turn the car off and grab the front wheels. Gently turn them lock to lock 10 times or so. That should help free them up.