So, the people we purchased our house from, laid underfloor heating and then put oak floorboards on top. We have now seen that there are two or three areas where the floorboards have come up a bit and are bouncy when you walk on them. We spoke to the previous owners recently, and they said (quiet amazingly) that they didn't fully level the floor before laying the UFH and subsequent floorboards, which has now led to this latest issue. Is there a way (an easy way) to rectify this? We have no intention of pulling everything up as that would be a massive upheaval.