Did the rods bind before you removed them?
If not, I'm with Pete. You may have reinstalled the eccentric crank in the wrong position. They are usually notched for position but can be installed 180 degrees off if your not careful/sure.
They only way to be sure is to use a photo of a similar Loco for reference and install the rods the same way provided the wheels are in the exact same position as in the photo.
Ideally photos of both sides of the drivers.
If you are unable to "google" a photo, maybe a fellow forum member could post some on this thread.
