Need to raise nut height Advice needed

How to replace a guitar nut guitar nut slot Choose nut slotting files that are the same size or no more that a few thousands larger than your individual string gauges A smaller file can also be rocked guitar nut slot depth Guitar fingerboard blank EU maple, slotted with and 21 frets Material: EU maple Scale length: 25,5 647,7mm

guitar nut slot When I pull the string quite hard afterwards, it's almost back in tune Could it be that the nut slots are too narrow for the thicker strings