Blend door

I'm having the heat control problem that has been explained by a broken blend door. I tried the fix that involved removing the actuater, drilling a hole, and inserting a nail. I tried three different holes and could not get the problem solved. The box seemed to snap back into place without any issues with the nail in, and the actuator was rotating when I turned the heat from hot to cold, but when I put the box back in, there was no change in the temperature. I followed the directions to a T, with no results. Any other suggestions????