steering servos does not return to center
 

im running both stock servos on a 3905 emaxx. with my truck on its lid...i turn left fully itll return back to center, but when i turn right fully, itll return past the center mark..the tires are now turned towards the left a little bit.
this is buggin me , i checked all linkages to make sure theyr e the right length..dunno how to fix this ..any help?