I have a DW735, which is similar, but not the same.
I would not recommend grinding anything off until long after you have completed all of the careful troubleshooting you can do first. ... and then think about it some more before grinding.
-> In my opinion, something isn't right, and grinding isn't the fix.
Here are some basic questions:
* With the planer unplugged, can you use your hand to raise and lower the material removal bar to move the red material removal gauge needle all the way between 0 and 1/8 inch? Is the material removal bar stuck? Is the material removal gauge needle stuck? Could there be sawdust or chips interfering with the bar or needle?
* Is the material removal gauge needle accurate? When you lower the planer and the needle says it will take off 1/32 or 1/16 inch, is the actual measurement "in the ballpark"? Use calipers to check the thickness before and after planing. Try a small cut. Also try a large cut where the board is near the top of the opening, but not scraping that part that hangs down a little. How much is actually removed?
* Are the correct blades installed? Are they genuine DeWalt blades or could they be aftermarket blades that might be the wrong dimension? Have the edges been ground down or resharpened to make them less "tall" than new blades? (Note: There is nothing wrong with aftermarket blades, as long as they match the specs of the originals.)
* When you open the top to inspect the blades, does everything look right inside the planer?
* Are you remembering to lock and unlock the planer before making height adjustments? (Note, it applies to the DW734, but not the DW735.)