I can think of a few things to check before sending it in.
1) Typically after 4-6 months the pump will build up enough calcium to need a thorough cleaning, be especially sure the hole in the magnet and the shaft it spins on in the pump are clean, a soak in 50/50 vinegar and water for a few hours and brushing the hole in the drive unit out with a small brush or pipe cleaners should do the job. Do not use a stronger acid, the plastic will swell as a result, only vinegar or citric acid should be used.
2) The power connection may be loose, make sure it is firmly attached and does not easily fall out, this can be adjusted easily if it is loose.
3) Check if when it shuts off, the light on the power supply turns off or blinks, this will usually point to issue 1, but can also mean that the power connection has some corrosion.
4) Make sure the disk 6055.740 is down in the pump on the shaft, the black plastic disk faces the bottom of the prop magnet. If this is missing (fell out at some point during cleaning) this can cause a stoppage either because the impeller is dragging on the silicon piece or rubbing on the plastic of the pump. Use a flashlight to look in the pump for this part. If it was reinstalled upside down so the silicon is facing the bottom of the drive magnet, that will also be a possible cause. The silicon is a noise dampner and the hard black plastic is what needs to contact the base of the magnet.
