Belt from nema pulley to Smooth idler not straight?

Are all the nema 23’s that go on the X-carve the same shaft length? Seems like the
25311-05 140oz-in does not have enough distance to keep the belt straight with the wheels. when looking at it the pulley shaft and Smooth Idler Pulley Assembly. The shaft or pulley from the Nema is suppose to line up to keep belt straight or is it I’m not looking at it the right way?

A photo would help.

I could try that very hard to get one seeing there is only the small hole on top to see.