We do not cover the warranty for Kelvin-units anymore since it has not been sold for a few years now, but if you pump is faulty, Aquatuning has compatible replacement pumps for it: https://www.aquatuning.co.uk/water-cooling/pumps/alphacool-dc-lt/dc-lt-pumps/20729/alphacool-dc-lt-2600-ultra-low-noise-ceramic-12v-dc
Below is a step by step guide as to how you replace the pump:
1, Pry off the plastic badge with the Fractal Design logo. It is glued in place but shouldn't be too hard to remove. Use something plastic if possible to minimize the damage.