Last year I replaced some old original floorboards in the upstairs landing. The old ones were split and therefore you could see the groove in the carpet where the gap formed. Anyway the old boards were tongue & groove style but the new ones I used were not. I screwed new ones down but now there is a groove in some places because for some reason the new ones are not level as the old ones and u can actually see the carpet level slightly go down ..........any ideas as to how to rectify. Thanks.