In between watching threads on 300K for 100K and Best Thread of Year (and anything from @Stizzla), I decided to do a complete kitchen reno . It is actually going well with new subfloor, underlayment and electrical moved. I cut back the pre-existing laminate floor that bordered the kitchen floor by 1' to increase the footprint of the kitchen. Prior to doing this, the laminate lay flat and has been stable for the last decade. It was still 'normal' when the transition strips were removed between the laminate and the kitchen. However, once the 1' was cut back (10' on one edge and 6' on the perpendicular edge), the longer edge has become springy ie it now has a bounce of approximately 3mm to it. There is appropriate relief around the edges and it only is on the longer side (which runs perpendicular to how the laminate lays). I checked the support underneath and all appear to be cupped properly. I would like to remove this bounce prior to installing the kitchen floor and new transition strips. I am very close to taking my air gun and setting in a strip of 2" staples along the edge to tuck it down and cover the staples with the transition strip. Not fine carpentry but it was not an issue prior to cutting back so I cannot understand why it has this small bounce. Does anyone have any other ideas? Thanks!