My mistake, sorry. I did not want to go through tall of the redundancy from the beginning.
I thought the sled was the melamine part and that you simply had lumber sitting on top. I now see that the large piece has the stop on the far end. ;~)
Got it! LOL sorry you had to repeat yourself to me, again.
If you are continuing to have issues it is probably a situation where you are going to be wasting time trying to get more out of a bench top planer. I never expected my bench top planer to do anything besides change the thickness of a "flat" board.
AND FWIW flattening a board on my 15" stationary planer is not a pleasurable thing either. Technically that is the job of a jointer but that is another story.
Moving the sled and work with out disturbing the shims takes considerably more time and effort than it is worth, for me.