Frage Bed or portal on SC-2 420 is not 100% flat

My SC-2 420 is working fine, and I really enjoy it, but I've encounter an issue I would like to correct.

When I do a cut-trough on a sheet of mdf, the parts on the left are well cut, but on the right, the pieces are often still attached to the sheet by a thin film: the (cut-down end-miller) bit doesn't go through completely. I have to cut the film with a knife to detach the components.

So my question: do I have to unscrew the portal to reset the position, or what else can I do to correct this?
Ok, I could cut down a little deeper, but I want to correct the level differences.

Best strategy is not to play with the setup as you will have tuned it.

mount a piece of MDF on the table.

Drill and tap into the bed. Counter sink the holes well below the surface. Make sure the MDF is held in the middle also.

Skim the bed flat with the machine (pocket toolpath)

then the surface will be flat relative to the cutting plane of the STEPPI

also - its hard to assume your workpiece is always flat. It can be the clamping.

For perfect results (even on other machines) vacuum clamping and skimming the vacuum table is the best method.

Strange thing, but the issue seems to be gone now.
I don't understand why, but I'm happy I didn't unscrew anything yet.

And indeed, the material could have some defaults too.

Since I'm using down-cut end millers, it's possible the material is accumulating below the sheet and lift it a little.

So i will plan to do this for my Stepcraft .