Vonqualen

On a newly purchased planer, I’m finding marks(long grooves or scratches) on the BOTTOM of the board. Have tried it with and without the leading and following trays. The bottom of the tray is clean, no burrs or any thing to cause the problem. Sounds crazy I realize, but had a friend look at it and couldn’t figure out the problem either. Shows up on both hardwood and softwood slabs. Anyone else have this situation?