Step Scale went out the window

So I've been cutting with no issues, recently cut a sign design that was 91.125" long Y axis metal came off the table at exactly 91.125" long. than last night I went to cut some basic holes and a piece that was 74 inches long with the metal pre-marked where the holes should be and noticed it was not moving to cut in that spot. verified the drawing and it was correct. ran the y axis from 0 - 36" and it ran to 36.25". short of redoing my config to get the correct distance again what would cause it to just say oh I'm not running on those numbers anymore. lol  I know it could be missing steps and if it is doing this is there a way to identify it. I wouldn't expect this to be the case as the distance is repeatable to the same distance each time. 

ok so when i set this all up it was foreign until it wasn't and know its foreign again. I look at the step conf wizard and input the info the best I remembered . I have 3:1 on rack n pinion stepping at 16 motors are 1.8 so input 200 this returns something like 9600 which is way off from what im actually running 2793 on step scale. ran some testing until i had it dialed in to 2778 step scale and now its back to hitting 36" and 72" give or take 1/16 or best a tape measurer can provide. Im guessing in the step conf wizard im entering bad info since the step scale is so far off from my real world example. still not sure why I would be hitting spot on for over a year and than all of a sudden need to make a minor step scale change.

What drives are you using?

DM542T I believe the first version. like 2.4 I saw there is a new version to this drive like 4.3 or something. Oh Stepperonline drivers