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.
2, Unscrew the four screws underneath the plastic cover.
3, Remove the rubber seal.
4, Unscrew the two screws holding the pump in place
5, Remove the pump, this is where you'll get in contact with the water. Make sure you keep the pump at the highest point and level to minimize the spill. It can help to have a buddy hold the pump housing elevated for you when doing this.
6, Reassemble in reversed order and top up with distilled water to make sure it is entirely filled.