Yesterday, in preparation for fixing the floorboards, I had to adjust the height of floor 3 by about 4 mm. I just glued a strip of wood onto the top. Once I have cleaned this all up and it is painted, no-one will ever know. The white line is just a bit of masking tape. The bottom edge of the tape is the line where the floor boards (will) touch the bottom panel. The tape shows clearly that floor 3 was too low … Once the clamps are off, I will adjust the tape.