Cutting depth issue

When cutting from left to right, the depth of my cut remains the same, when cutting from front to back, I lose about 1.41mm in the depth of the cut. Therefore I lose some detail. Can someone PLEASE tell me what I need to adjust and how, PLEASE!

Is the 1.41 all the way back of the board, or is the 1.41 in the middle of the machine?
Check with calipers whether or not the rails are even along the edges of the board.
If there is a drop at the other end, see if the end-plates of the rails are flush with the bottom frame to begin with.

Thanks for the help … I’ll do some further checking and advice exactly where the 1.41mm difference is and the position of the rail end-plates.